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buf_size: fix handling of 1 element arrays
[smatch.git] / smatch_extra.c
blobd611b9b73abd2615ded5f41f6b49c79913ead71c
1 /*
2 * Copyright (C) 2008 Dan Carpenter.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
16 */
17
18 /*
19 * smatch_extra.c is supposed to track the value of every variable.
20 *
21 */
22
23 #define _GNU_SOURCE
24 #include <string.h>
25
26 #include <stdlib.h>
27 #include <errno.h>
28 #ifndef __USE_ISOC99
29 #define __USE_ISOC99
30 #endif
31 #include <limits.h>
32 #include "parse.h"
33 #include "smatch.h"
34 #include "smatch_slist.h"
35 #include "smatch_extra.h"
36
37 static int my_id;
38 static int link_id;
39
40 static void match_link_modify(struct sm_state *sm, struct expression *mod_expr);
41
42 struct string_list *__ignored_macros = NULL;
43 static int in_warn_on_macro(void)
44 {
45 struct statement *stmt;
46 char *tmp;
47 char *macro;
48
49 stmt = get_current_statement();
50 if (!stmt)
51 return 0;
52 macro = get_macro_name(stmt->pos);
53 if (!macro)
54 return 0;
55
56 FOR_EACH_PTR(__ignored_macros, tmp) {
57 if (!strcmp(tmp, macro))
58 return 1;
59 } END_FOR_EACH_PTR(tmp);
60 return 0;
61 }
62
63 typedef void (mod_hook)(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state);
64 DECLARE_PTR_LIST(void_fn_list, mod_hook *);
65 static struct void_fn_list *extra_mod_hooks;
66 static struct void_fn_list *extra_nomod_hooks;
67
68 void add_extra_mod_hook(mod_hook *fn)
69 {
70 mod_hook **p = malloc(sizeof(mod_hook *));
71 *p = fn;
72 add_ptr_list(&extra_mod_hooks, p);
73 }
74
75 void add_extra_nomod_hook(mod_hook *fn)
76 {
77 mod_hook **p = malloc(sizeof(mod_hook *));
78 *p = fn;
79 add_ptr_list(&extra_nomod_hooks, p);
80 }
81
82 void call_extra_hooks(struct void_fn_list *hooks, const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
83 {
84 mod_hook **fn;
85
86 FOR_EACH_PTR(hooks, fn) {
87 (*fn)(name, sym, expr, state);
88 } END_FOR_EACH_PTR(fn);
89 }
90
91 void call_extra_mod_hooks(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
92 {
93 call_extra_hooks(extra_mod_hooks, name, sym, expr, state);
94 }
95
96 void call_extra_nomod_hooks(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
97 {
98 call_extra_hooks(extra_nomod_hooks, name, sym, expr, state);
99 }
100
101 static bool in_param_set;
102 void set_extra_mod_helper(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
103 {
104 remove_from_equiv(name, sym);
105 call_extra_mod_hooks(name, sym, expr, state);
106 if ((__in_fake_assign || in_param_set) &&
107 estate_is_unknown(state) && !get_state(SMATCH_EXTRA, name, sym))
108 return;
109 set_state(SMATCH_EXTRA, name, sym, state);
110 }
111
112 static void set_extra_nomod_helper(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
113 {
114 call_extra_nomod_hooks(name, sym, expr, state);
115 set_state(SMATCH_EXTRA, name, sym, state);
116 }
117
118 static char *get_pointed_at(const char *name, struct symbol *sym, struct symbol **new_sym)
119 {
120 struct expression *assigned;
121
122 if (name[0] != '*')
123 return NULL;
124 if (strcmp(name + 1, sym->ident->name) != 0)
125 return NULL;
126
127 assigned = get_assigned_expr_name_sym(sym->ident->name, sym);
128 if (!assigned)
129 return NULL;
130 assigned = strip_parens(assigned);
131 if (assigned->type != EXPR_PREOP || assigned->op != '&')
132 return NULL;
133
134 return expr_to_var_sym(assigned->unop, new_sym);
135 }
136
137 char *get_other_name_sym(const char *name, struct symbol *sym, struct symbol **new_sym)
138 {
139 struct expression *assigned;
140 char *orig_name = NULL;
141 char buf[256];
142 char *ret = NULL;
143 int skip;
144
145 *new_sym = NULL;
146
147 if (!sym || !sym->ident)
148 return NULL;
149
150 ret = get_pointed_at(name, sym, new_sym);
151 if (ret)
152 return ret;
153
154 skip = strlen(sym->ident->name);
155 if (name[skip] != '-' || name[skip + 1] != '>')
156 return NULL;
157 skip += 2;
158
159 assigned = get_assigned_expr_name_sym(sym->ident->name, sym);
160 if (!assigned)
161 return NULL;
162 if (assigned->type == EXPR_CALL)
163 return map_call_to_other_name_sym(name, sym, new_sym);
164 if (assigned->type == EXPR_PREOP || assigned->op == '&') {
165
166 orig_name = expr_to_var_sym(assigned, new_sym);
167 if (!orig_name || !*new_sym)
168 goto free;
169
170 snprintf(buf, sizeof(buf), "%s.%s", orig_name + 1, name + skip);
171 ret = alloc_string(buf);
172 free_string(orig_name);
173 return ret;
174 }
175
176 if (assigned->type != EXPR_DEREF)
177 goto free;
178
179 orig_name = expr_to_var_sym(assigned, new_sym);
180 if (!orig_name || !*new_sym)
181 goto free;
182
183 snprintf(buf, sizeof(buf), "%s->%s", orig_name, name + skip);
184 ret = alloc_string(buf);
185 free_string(orig_name);
186 return ret;
187
188 free:
189 free_string(orig_name);
190 return NULL;
191 }
192
193 void set_extra_mod(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
194 {
195 char *new_name;
196 struct symbol *new_sym;
197
198 set_extra_mod_helper(name, sym, expr, state);
199 new_name = get_other_name_sym(name, sym, &new_sym);
200 if (new_name && new_sym)
201 set_extra_mod_helper(new_name, new_sym, expr, state);
202 free_string(new_name);
203 }
204
205 static struct expression *chunk_get_array_base(struct expression *expr)
206 {
207 /*
208 * The problem with is_array() is that it only returns true for things
209 * like foo[1] but not for foo[1].bar.
210 *
211 */
212 expr = strip_expr(expr);
213 while (expr && expr->type == EXPR_DEREF)
214 expr = strip_expr(expr->deref);
215 return get_array_base(expr);
216 }
217
218 static int chunk_has_array(struct expression *expr)
219 {
220 return !!chunk_get_array_base(expr);
221 }
222
223 static void clear_array_states(struct expression *array)
224 {
225 struct sm_state *sm;
226
227 sm = get_sm_state_expr(link_id, array);
228 if (sm)
229 match_link_modify(sm, NULL);
230 }
231
232 static void set_extra_array_mod(struct expression *expr, struct smatch_state *state)
233 {
234 struct expression *array;
235 struct var_sym_list *vsl;
236 struct var_sym *vs;
237 char *name;
238 struct symbol *sym;
239
240 array = chunk_get_array_base(expr);
241
242 name = expr_to_chunk_sym_vsl(expr, &sym, &vsl);
243 if (!name || !vsl) {
244 clear_array_states(array);
245 goto free;
246 }
247
248 FOR_EACH_PTR(vsl, vs) {
249 store_link(link_id, vs->var, vs->sym, name, sym);
250 } END_FOR_EACH_PTR(vs);
251
252 call_extra_mod_hooks(name, sym, expr, state);
253 set_state(SMATCH_EXTRA, name, sym, state);
254 free:
255 free_string(name);
256 }
257
258 void set_extra_expr_mod(struct expression *expr, struct smatch_state *state)
259 {
260 struct symbol *sym;
261 char *name;
262
263 if (chunk_has_array(expr)) {
264 set_extra_array_mod(expr, state);
265 return;
266 }
267
268 expr = strip_expr(expr);
269 name = expr_to_var_sym(expr, &sym);
270 if (!name || !sym)
271 goto free;
272 set_extra_mod(name, sym, expr, state);
273 free:
274 free_string(name);
275 }
276
277 void set_extra_nomod(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
278 {
279 char *new_name;
280 struct symbol *new_sym;
281 struct relation *rel;
282 struct smatch_state *orig_state;
283
284 orig_state = get_state(SMATCH_EXTRA, name, sym);
285
286 /* don't save unknown states if leaving it blank is the same */
287 if (!orig_state && estate_is_unknown(state))
288 return;
289
290 new_name = get_other_name_sym(name, sym, &new_sym);
291 if (new_name && new_sym)
292 set_extra_nomod_helper(new_name, new_sym, expr, state);
293 free_string(new_name);
294
295 if (!estate_related(orig_state)) {
296 set_extra_nomod_helper(name, sym, expr, state);
297 return;
298 }
299
300 set_related(state, estate_related(orig_state));
301 FOR_EACH_PTR(estate_related(orig_state), rel) {
302 struct smatch_state *estate;
303
304 if (option_debug_related)
305 sm_msg("%s updating related %s to %s", name, rel->name, state->name);
306 estate = get_state(SMATCH_EXTRA, rel->name, rel->sym);
307 if (!estate)
308 continue;
309 set_extra_nomod_helper(rel->name, rel->sym, expr, clone_estate_cast(estate_type(estate), state));
310 } END_FOR_EACH_PTR(rel);
311 }
312
313 void set_extra_nomod_vsl(const char *name, struct symbol *sym, struct var_sym_list *vsl, struct expression *expr, struct smatch_state *state)
314 {
315 struct var_sym *vs;
316
317 FOR_EACH_PTR(vsl, vs) {
318 store_link(link_id, vs->var, vs->sym, name, sym);
319 } END_FOR_EACH_PTR(vs);
320
321 set_extra_nomod(name, sym, expr, state);
322 }
323
324 /*
325 * This is for return_implies_state() hooks which modify a SMATCH_EXTRA state
326 */
327 void set_extra_expr_nomod(struct expression *expr, struct smatch_state *state)
328 {
329 struct var_sym_list *vsl;
330 struct var_sym *vs;
331 char *name;
332 struct symbol *sym;
333
334 name = expr_to_chunk_sym_vsl(expr, &sym, &vsl);
335 if (!name || !vsl)
336 goto free;
337 FOR_EACH_PTR(vsl, vs) {
338 store_link(link_id, vs->var, vs->sym, name, sym);
339 } END_FOR_EACH_PTR(vs);
340
341 set_extra_nomod(name, sym, expr, state);
342 free:
343 free_string(name);
344 }
345
346 static void set_extra_true_false(const char *name, struct symbol *sym,
347 struct smatch_state *true_state,
348 struct smatch_state *false_state)
349 {
350 char *new_name;
351 struct symbol *new_sym;
352 struct relation *rel;
353 struct smatch_state *orig_state;
354
355 if (!true_state && !false_state)
356 return;
357
358 if (in_warn_on_macro())
359 return;
360
361 new_name = get_other_name_sym(name, sym, &new_sym);
362 if (new_name && new_sym)
363 set_true_false_states(SMATCH_EXTRA, new_name, new_sym, true_state, false_state);
364 free_string(new_name);
365
366 orig_state = get_state(SMATCH_EXTRA, name, sym);
367
368 if (!estate_related(orig_state)) {
369 set_true_false_states(SMATCH_EXTRA, name, sym, true_state, false_state);
370 return;
371 }
372
373 if (true_state)
374 set_related(true_state, estate_related(orig_state));
375 if (false_state)
376 set_related(false_state, estate_related(orig_state));
377
378 FOR_EACH_PTR(estate_related(orig_state), rel) {
379 set_true_false_states(SMATCH_EXTRA, rel->name, rel->sym,
380 true_state, false_state);
381 } END_FOR_EACH_PTR(rel);
382 }
383
384 static void set_extra_chunk_true_false(struct expression *expr,
385 struct smatch_state *true_state,
386 struct smatch_state *false_state)
387 {
388 struct var_sym_list *vsl;
389 struct var_sym *vs;
390 struct symbol *type;
391 char *name;
392 struct symbol *sym;
393
394 if (in_warn_on_macro())
395 return;
396
397 type = get_type(expr);
398 if (!type)
399 return;
400
401 name = expr_to_chunk_sym_vsl(expr, &sym, &vsl);
402 if (!name || !vsl)
403 goto free;
404 FOR_EACH_PTR(vsl, vs) {
405 store_link(link_id, vs->var, vs->sym, name, sym);
406 } END_FOR_EACH_PTR(vs);
407
408 set_true_false_states(SMATCH_EXTRA, name, sym,
409 clone_estate(true_state),
410 clone_estate(false_state));
411 free:
412 free_string(name);
413 }
414
415 static void set_extra_expr_true_false(struct expression *expr,
416 struct smatch_state *true_state,
417 struct smatch_state *false_state)
418 {
419 char *name;
420 struct symbol *sym;
421 sval_t sval;
422
423 if (!true_state && !false_state)
424 return;
425
426 if (get_value(expr, &sval))
427 return;
428
429 expr = strip_expr(expr);
430 name = expr_to_var_sym(expr, &sym);
431 if (!name || !sym) {
432 free_string(name);
433 set_extra_chunk_true_false(expr, true_state, false_state);
434 return;
435 }
436 set_extra_true_false(name, sym, true_state, false_state);
437 free_string(name);
438 }
439
440 static int get_countdown_info(struct expression *condition, struct expression **unop, int *op, sval_t *right)
441 {
442 struct expression *unop_expr;
443 int comparison;
444 sval_t limit;
445
446 right->type = &int_ctype;
447 right->value = 0;
448
449 condition = strip_expr(condition);
450
451 if (condition->type == EXPR_COMPARE) {
452 comparison = remove_unsigned_from_comparison(condition->op);
453
454 if (comparison != SPECIAL_GTE && comparison != '>')
455 return 0;
456 if (!get_value(condition->right, &limit))
457 return 0;
458
459 unop_expr = condition->left;
460 if (unop_expr->type != EXPR_PREOP && unop_expr->type != EXPR_POSTOP)
461 return 0;
462 if (unop_expr->op != SPECIAL_DECREMENT)
463 return 0;
464
465 *unop = unop_expr;
466 *op = comparison;
467 *right = limit;
468
469 return 1;
470 }
471
472 if (condition->type != EXPR_PREOP && condition->type != EXPR_POSTOP)
473 return 0;
474 if (condition->op != SPECIAL_DECREMENT)
475 return 0;
476
477 *unop = condition;
478 *op = '>';
479
480 return 1;
481 }
482
483 static struct sm_state *handle_canonical_while_count_down(struct statement *loop)
484 {
485 struct expression *iter_var;
486 struct expression *condition, *unop;
487 struct sm_state *sm;
488 struct smatch_state *estate;
489 int op;
490 sval_t start, right;
491
492 right.type = &int_ctype;
493 right.value = 0;
494
495 condition = strip_expr(loop->iterator_pre_condition);
496 if (!condition)
497 return NULL;
498
499 if (!get_countdown_info(condition, &unop, &op, &right))
500 return NULL;
501
502 iter_var = unop->unop;
503
504 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
505 if (!sm)
506 return NULL;
507 if (sval_cmp(estate_min(sm->state), right) < 0)
508 return NULL;
509 start = estate_max(sm->state);
510 if (sval_cmp(start, right) <= 0)
511 return NULL;
512 if (!sval_is_max(start))
513 start.value--;
514
515 if (op == SPECIAL_GTE)
516 right.value--;
517
518 if (unop->type == EXPR_PREOP) {
519 right.value++;
520 estate = alloc_estate_range(right, start);
521 if (estate_has_hard_max(sm->state))
522 estate_set_hard_max(estate);
523 estate_copy_fuzzy_max(estate, sm->state);
524 set_extra_expr_mod(iter_var, estate);
525 }
526 if (unop->type == EXPR_POSTOP) {
527 estate = alloc_estate_range(right, start);
528 if (estate_has_hard_max(sm->state))
529 estate_set_hard_max(estate);
530 estate_copy_fuzzy_max(estate, sm->state);
531 set_extra_expr_mod(iter_var, estate);
532 }
533 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
534 }
535
536 static struct sm_state *handle_canonical_for_inc(struct expression *iter_expr,
537 struct expression *condition)
538 {
539 struct expression *iter_var;
540 struct sm_state *sm;
541 struct smatch_state *estate;
542 sval_t start, end, max;
543
544 iter_var = iter_expr->unop;
545 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
546 if (!sm)
547 return NULL;
548 if (!estate_get_single_value(sm->state, &start))
549 return NULL;
550 if (get_implied_max(condition->right, &end))
551 end = sval_cast(get_type(iter_var), end);
552 else
553 end = sval_type_max(get_type(iter_var));
554
555 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
556 return NULL;
557
558 switch (condition->op) {
559 case SPECIAL_UNSIGNED_LT:
560 case SPECIAL_NOTEQUAL:
561 case '<':
562 if (!sval_is_min(end))
563 end.value--;
564 break;
565 case SPECIAL_UNSIGNED_LTE:
566 case SPECIAL_LTE:
567 break;
568 default:
569 return NULL;
570 }
571 if (sval_cmp(end, start) < 0)
572 return NULL;
573 estate = alloc_estate_range(start, end);
574 if (get_hard_max(condition->right, &max)) {
575 estate_set_hard_max(estate);
576 if (condition->op == '<' ||
577 condition->op == SPECIAL_UNSIGNED_LT ||
578 condition->op == SPECIAL_NOTEQUAL)
579 max.value--;
580 estate_set_fuzzy_max(estate, max);
581 }
582 set_extra_expr_mod(iter_var, estate);
583 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
584 }
585
586 static struct sm_state *handle_canonical_for_dec(struct expression *iter_expr,
587 struct expression *condition)
588 {
589 struct expression *iter_var;
590 struct sm_state *sm;
591 struct smatch_state *estate;
592 sval_t start, end;
593
594 iter_var = iter_expr->unop;
595 sm = get_sm_state_expr(SMATCH_EXTRA, iter_var);
596 if (!sm)
597 return NULL;
598 if (!estate_get_single_value(sm->state, &start))
599 return NULL;
600 if (!get_implied_min(condition->right, &end))
601 end = sval_type_min(get_type(iter_var));
602 if (get_sm_state_expr(SMATCH_EXTRA, condition->left) != sm)
603 return NULL;
604
605 switch (condition->op) {
606 case SPECIAL_NOTEQUAL:
607 case '>':
608 if (!sval_is_min(end) && !sval_is_max(end))
609 end.value++;
610 break;
611 case SPECIAL_GTE:
612 break;
613 default:
614 return NULL;
615 }
616 if (sval_cmp(end, start) > 0)
617 return NULL;
618 estate = alloc_estate_range(end, start);
619 estate_set_hard_max(estate);
620 estate_set_fuzzy_max(estate, estate_get_fuzzy_max(estate));
621 set_extra_expr_mod(iter_var, estate);
622 return get_sm_state_expr(SMATCH_EXTRA, iter_var);
623 }
624
625 static struct sm_state *handle_canonical_for_loops(struct statement *loop)
626 {
627 struct expression *iter_expr;
628 struct expression *condition;
629
630 if (!loop->iterator_post_statement)
631 return NULL;
632 if (loop->iterator_post_statement->type != STMT_EXPRESSION)
633 return NULL;
634 iter_expr = loop->iterator_post_statement->expression;
635 if (!loop->iterator_pre_condition)
636 return NULL;
637 if (loop->iterator_pre_condition->type != EXPR_COMPARE)
638 return NULL;
639 condition = loop->iterator_pre_condition;
640
641 if (iter_expr->op == SPECIAL_INCREMENT)
642 return handle_canonical_for_inc(iter_expr, condition);
643 if (iter_expr->op == SPECIAL_DECREMENT)
644 return handle_canonical_for_dec(iter_expr, condition);
645 return NULL;
646 }
647
648 struct sm_state *__extra_handle_canonical_loops(struct statement *loop, struct stree **stree)
649 {
650 struct sm_state *ret;
651
652 /*
653 * Canonical loops are a hack. The proper way to handle this is to
654 * use two passes, but unfortunately, doing two passes makes parsing
655 * code twice as slow.
656 *
657 * What we do is we set the inside state here, which overwrites whatever
658 * __extra_match_condition() does. Then we set the outside state in
659 * __extra_pre_loop_hook_after().
660 *
661 */
662 __push_fake_cur_stree();
663 if (!loop->iterator_post_statement)
664 ret = handle_canonical_while_count_down(loop);
665 else
666 ret = handle_canonical_for_loops(loop);
667 *stree = __pop_fake_cur_stree();
668 return ret;
669 }
670
671 int __iterator_unchanged(struct sm_state *sm)
672 {
673 if (!sm)
674 return 0;
675 if (get_sm_state(my_id, sm->name, sm->sym) == sm)
676 return 1;
677 return 0;
678 }
679
680 static void while_count_down_after(struct sm_state *sm, struct expression *condition)
681 {
682 struct expression *unop;
683 int op;
684 sval_t limit, after_value;
685
686 if (!get_countdown_info(condition, &unop, &op, &limit))
687 return;
688 after_value = estate_min(sm->state);
689 after_value.value--;
690 set_extra_mod(sm->name, sm->sym, condition->unop, alloc_estate_sval(after_value));
691 }
692
693 void __extra_pre_loop_hook_after(struct sm_state *sm,
694 struct statement *iterator,
695 struct expression *condition)
696 {
697 struct expression *iter_expr;
698 sval_t limit;
699 struct smatch_state *state;
700
701 if (!iterator) {
702 while_count_down_after(sm, condition);
703 return;
704 }
705
706 iter_expr = iterator->expression;
707
708 if (condition->type != EXPR_COMPARE)
709 return;
710 if (iter_expr->op == SPECIAL_INCREMENT) {
711 limit = sval_binop(estate_max(sm->state), '+',
712 sval_type_val(estate_type(sm->state), 1));
713 } else {
714 limit = sval_binop(estate_min(sm->state), '-',
715 sval_type_val(estate_type(sm->state), 1));
716 }
717 if (!estate_has_hard_max(sm->state) && !__has_breaks()) {
718 if (iter_expr->op == SPECIAL_INCREMENT)
719 state = alloc_estate_range(estate_min(sm->state), limit);
720 else
721 state = alloc_estate_range(limit, estate_max(sm->state));
722 } else {
723 state = alloc_estate_sval(limit);
724 }
725 if (!estate_has_hard_max(sm->state)) {
726 estate_clear_hard_max(state);
727 }
728 if (estate_has_fuzzy_max(sm->state)) {
729 sval_t hmax = estate_get_fuzzy_max(sm->state);
730 sval_t max = estate_max(sm->state);
731
732 if (sval_cmp(hmax, max) != 0)
733 estate_clear_fuzzy_max(state);
734 } else if (!estate_has_fuzzy_max(sm->state)) {
735 estate_clear_fuzzy_max(state);
736 }
737
738 set_extra_mod(sm->name, sm->sym, iter_expr, state);
739 }
740
741 static struct stree *unmatched_stree;
742 static struct smatch_state *unmatched_state(struct sm_state *sm)
743 {
744 struct smatch_state *state;
745
746 if (unmatched_stree) {
747 state = get_state_stree(unmatched_stree, SMATCH_EXTRA, sm->name, sm->sym);
748 if (state)
749 return state;
750 }
751 if (parent_is_gone_var_sym(sm->name, sm->sym))
752 return alloc_estate_empty();
753 return alloc_estate_whole(estate_type(sm->state));
754 }
755
756 static void clear_the_pointed_at(struct expression *expr)
757 {
758 struct stree *stree;
759 char *name;
760 struct symbol *sym;
761 struct sm_state *tmp;
762
763 name = expr_to_var_sym(expr, &sym);
764 if (!name || !sym)
765 goto free;
766
767 stree = __get_cur_stree();
768 FOR_EACH_MY_SM(SMATCH_EXTRA, stree, tmp) {
769 if (tmp->name[0] != '*')
770 continue;
771 if (tmp->sym != sym)
772 continue;
773 if (strcmp(tmp->name + 1, name) != 0)
774 continue;
775 set_extra_mod(tmp->name, tmp->sym, expr, alloc_estate_whole(estate_type(tmp->state)));
776 } END_FOR_EACH_SM(tmp);
777
778 free:
779 free_string(name);
780 }
781
782 static int is_const_param(struct expression *expr, int param)
783 {
784 struct symbol *type;
785
786 type = get_arg_type(expr, param);
787 if (!type)
788 return 0;
789 if (type->ctype.modifiers & MOD_CONST)
790 return 1;
791 return 0;
792 }
793
794 static void match_function_call(struct expression *expr)
795 {
796 struct expression *arg;
797 struct expression *tmp;
798 int param = -1;
799
800 /* if we have the db this is handled in smatch_function_hooks.c */
801 if (!option_no_db)
802 return;
803 if (inlinable(expr->fn))
804 return;
805
806 FOR_EACH_PTR(expr->args, arg) {
807 param++;
808 if (is_const_param(expr->fn, param))
809 continue;
810 tmp = strip_expr(arg);
811 if (tmp->type == EXPR_PREOP && tmp->op == '&')
812 set_extra_expr_mod(tmp->unop, alloc_estate_whole(get_type(tmp->unop)));
813 else
814 clear_the_pointed_at(tmp);
815 } END_FOR_EACH_PTR(arg);
816 }
817
818 static int values_fit_type(struct expression *left, struct expression *right)
819 {
820 struct range_list *rl;
821 struct symbol *type;
822
823 type = get_type(left);
824 if (!type)
825 return 0;
826 get_absolute_rl(right, &rl);
827 if (type_unsigned(type) && sval_is_negative(rl_min(rl)))
828 return 0;
829 if (sval_cmp(sval_type_min(type), rl_min(rl)) > 0)
830 return 0;
831 if (sval_cmp(sval_type_max(type), rl_max(rl)) < 0)
832 return 0;
833 return 1;
834 }
835
836 static void save_chunk_info(struct expression *left, struct expression *right)
837 {
838 struct var_sym_list *vsl;
839 struct var_sym *vs;
840 struct expression *add_expr;
841 struct symbol *type;
842 sval_t sval;
843 char *name;
844 struct symbol *sym;
845
846 if (right->type != EXPR_BINOP || right->op != '-')
847 return;
848 if (!get_value(right->left, &sval))
849 return;
850 if (!expr_to_sym(right->right))
851 return;
852
853 add_expr = binop_expression(left, '+', right->right);
854 type = get_type(add_expr);
855 if (!type)
856 return;
857 name = expr_to_chunk_sym_vsl(add_expr, &sym, &vsl);
858 if (!name || !vsl)
859 goto free;
860 FOR_EACH_PTR(vsl, vs) {
861 store_link(link_id, vs->var, vs->sym, name, sym);
862 } END_FOR_EACH_PTR(vs);
863
864 set_state(SMATCH_EXTRA, name, sym, alloc_estate_sval(sval_cast(type, sval)));
865 free:
866 free_string(name);
867 }
868
869 static void do_array_assign(struct expression *left, int op, struct expression *right)
870 {
871 struct range_list *rl;
872
873 if (op == '=') {
874 get_absolute_rl(right, &rl);
875 rl = cast_rl(get_type(left), rl);
876 } else {
877 rl = alloc_whole_rl(get_type(left));
878 }
879
880 set_extra_array_mod(left, alloc_estate_rl(rl));
881 }
882
883 static void match_vanilla_assign(struct expression *left, struct expression *right)
884 {
885 struct range_list *orig_rl = NULL;
886 struct range_list *rl = NULL;
887 struct symbol *right_sym;
888 struct symbol *left_type;
889 struct symbol *right_type;
890 char *right_name = NULL;
891 struct symbol *sym;
892 char *name;
893 sval_t sval, max;
894 struct smatch_state *state;
895 int comparison;
896
897 if (is_struct(left))
898 return;
899
900 save_chunk_info(left, right);
901
902 name = expr_to_var_sym(left, &sym);
903 if (!name) {
904 if (chunk_has_array(left))
905 do_array_assign(left, '=', right);
906 return;
907 }
908
909 left_type = get_type(left);
910 right_type = get_type(right);
911
912 right_name = expr_to_var_sym(right, &right_sym);
913
914 if (!__in_fake_assign &&
915 !(right->type == EXPR_PREOP && right->op == '&') &&
916 right_name && right_sym &&
917 values_fit_type(left, strip_expr(right)) &&
918 !has_symbol(right, sym)) {
919 set_equiv(left, right);
920 goto free;
921 }
922
923 if (is_pointer(right) && get_address_rl(right, &rl)) {
924 state = alloc_estate_rl(rl);
925 goto done;
926 }
927
928 if (get_implied_value(right, &sval)) {
929 state = alloc_estate_sval(sval_cast(left_type, sval));
930 goto done;
931 }
932
933 if (__in_fake_assign) {
934 struct smatch_state *right_state;
935 sval_t sval;
936
937 if (get_value(right, &sval)) {
938 sval = sval_cast(left_type, sval);
939 state = alloc_estate_sval(sval);
940 goto done;
941 }
942
943 right_state = get_state(SMATCH_EXTRA, right_name, right_sym);
944 if (right_state) {
945 /* simple assignment */
946 state = clone_estate(right_state);
947 goto done;
948 }
949
950 state = alloc_estate_rl(alloc_whole_rl(left_type));
951 goto done;
952 }
953
954 comparison = get_comparison(left, right);
955 if (comparison) {
956 comparison = flip_comparison(comparison);
957 get_implied_rl(left, &orig_rl);
958 }
959
960 if (get_implied_rl(right, &rl)) {
961 rl = cast_rl(left_type, rl);
962 if (orig_rl)
963 filter_by_comparison(&rl, comparison, orig_rl);
964 state = alloc_estate_rl(rl);
965 if (get_hard_max(right, &max)) {
966 estate_set_hard_max(state);
967 estate_set_fuzzy_max(state, max);
968 }
969 } else {
970 rl = alloc_whole_rl(right_type);
971 rl = cast_rl(left_type, rl);
972 if (orig_rl)
973 filter_by_comparison(&rl, comparison, orig_rl);
974 state = alloc_estate_rl(rl);
975 }
976
977 done:
978 set_extra_mod(name, sym, left, state);
979 free:
980 free_string(right_name);
981 }
982
983 static int op_remove_assign(int op)
984 {
985 switch (op) {
986 case SPECIAL_ADD_ASSIGN:
987 return '+';
988 case SPECIAL_SUB_ASSIGN:
989 return '-';
990 case SPECIAL_MUL_ASSIGN:
991 return '*';
992 case SPECIAL_DIV_ASSIGN:
993 return '/';
994 case SPECIAL_MOD_ASSIGN:
995 return '%';
996 case SPECIAL_AND_ASSIGN:
997 return '&';
998 case SPECIAL_OR_ASSIGN:
999 return '|';
1000 case SPECIAL_XOR_ASSIGN:
1001 return '^';
1002 case SPECIAL_SHL_ASSIGN:
1003 return SPECIAL_LEFTSHIFT;
1004 case SPECIAL_SHR_ASSIGN:
1005 return SPECIAL_RIGHTSHIFT;
1006 default:
1007 return op;
1008 }
1009 }
1010
1011 static void match_assign(struct expression *expr)
1012 {
1013 struct range_list *rl = NULL;
1014 struct expression *left;
1015 struct expression *right;
1016 struct expression *binop_expr;
1017 struct symbol *left_type;
1018 struct symbol *sym;
1019 char *name;
1020 sval_t left_min, left_max;
1021 sval_t right_min, right_max;
1022 sval_t res_min, res_max;
1023
1024 left = strip_expr(expr->left);
1025
1026 right = strip_parens(expr->right);
1027 if (right->type == EXPR_CALL && sym_name_is("__builtin_expect", right->fn))
1028 right = get_argument_from_call_expr(right->args, 0);
1029 while (right->type == EXPR_ASSIGNMENT && right->op == '=')
1030 right = strip_parens(right->left);
1031
1032 if (expr->op == '=' && is_condition(expr->right))
1033 return; /* handled in smatch_condition.c */
1034 if (expr->op == '=' && right->type == EXPR_CALL)
1035 return; /* handled in smatch_function_hooks.c */
1036 if (expr->op == '=') {
1037 match_vanilla_assign(left, right);
1038 return;
1039 }
1040
1041 name = expr_to_var_sym(left, &sym);
1042 if (!name)
1043 return;
1044
1045 left_type = get_type(left);
1046
1047 res_min = sval_type_min(left_type);
1048 res_max = sval_type_max(left_type);
1049
1050 switch (expr->op) {
1051 case SPECIAL_ADD_ASSIGN:
1052 get_absolute_max(left, &left_max);
1053 get_absolute_max(right, &right_max);
1054 if (sval_binop_overflows(left_max, '+', sval_cast(left_type, right_max)))
1055 break;
1056 if (get_implied_min(left, &left_min) &&
1057 !sval_is_negative_min(left_min) &&
1058 get_implied_min(right, &right_min) &&
1059 !sval_is_negative_min(right_min)) {
1060 res_min = sval_binop(left_min, '+', right_min);
1061 res_min = sval_cast(left_type, res_min);
1062 }
1063 if (inside_loop()) /* we are assuming loops don't lead to wrapping */
1064 break;
1065 res_max = sval_binop(left_max, '+', right_max);
1066 res_max = sval_cast(left_type, res_max);
1067 break;
1068 case SPECIAL_SUB_ASSIGN:
1069 if (get_implied_max(left, &left_max) &&
1070 !sval_is_max(left_max) &&
1071 get_implied_min(right, &right_min) &&
1072 !sval_is_min(right_min)) {
1073 res_max = sval_binop(left_max, '-', right_min);
1074 res_max = sval_cast(left_type, res_max);
1075 }
1076 if (inside_loop())
1077 break;
1078 if (get_implied_min(left, &left_min) &&
1079 !sval_is_min(left_min) &&
1080 get_implied_max(right, &right_max) &&
1081 !sval_is_max(right_max)) {
1082 res_min = sval_binop(left_min, '-', right_max);
1083 res_min = sval_cast(left_type, res_min);
1084 }
1085 break;
1086 case SPECIAL_AND_ASSIGN:
1087 case SPECIAL_MOD_ASSIGN:
1088 case SPECIAL_SHL_ASSIGN:
1089 case SPECIAL_SHR_ASSIGN:
1090 case SPECIAL_OR_ASSIGN:
1091 case SPECIAL_XOR_ASSIGN:
1092 case SPECIAL_MUL_ASSIGN:
1093 case SPECIAL_DIV_ASSIGN:
1094 binop_expr = binop_expression(expr->left,
1095 op_remove_assign(expr->op),
1096 expr->right);
1097 if (get_absolute_rl(binop_expr, &rl)) {
1098 rl = cast_rl(left_type, rl);
1099 set_extra_mod(name, sym, left, alloc_estate_rl(rl));
1100 goto free;
1101 }
1102 break;
1103 }
1104 rl = cast_rl(left_type, alloc_rl(res_min, res_max));
1105 set_extra_mod(name, sym, left, alloc_estate_rl(rl));
1106 free:
1107 free_string(name);
1108 }
1109
1110 static struct smatch_state *increment_state(struct smatch_state *state)
1111 {
1112 sval_t min = estate_min(state);
1113 sval_t max = estate_max(state);
1114
1115 if (!estate_rl(state))
1116 return NULL;
1117
1118 if (inside_loop())
1119 max = sval_type_max(max.type);
1120
1121 if (!sval_is_min(min) && !sval_is_max(min))
1122 min.value++;
1123 if (!sval_is_min(max) && !sval_is_max(max))
1124 max.value++;
1125 return alloc_estate_range(min, max);
1126 }
1127
1128 static struct smatch_state *decrement_state(struct smatch_state *state)
1129 {
1130 sval_t min = estate_min(state);
1131 sval_t max = estate_max(state);
1132
1133 if (!estate_rl(state))
1134 return NULL;
1135
1136 if (inside_loop())
1137 min = sval_type_min(min.type);
1138
1139 if (!sval_is_min(min) && !sval_is_max(min))
1140 min.value--;
1141 if (!sval_is_min(max) && !sval_is_max(max))
1142 max.value--;
1143 return alloc_estate_range(min, max);
1144 }
1145
1146 static void clear_pointed_at_state(struct expression *expr)
1147 {
1148 struct symbol *type;
1149
1150 /*
1151 * ALERT: This is sort of a mess. If it's is a struct assigment like
1152 * "foo = bar;", then that's handled by smatch_struct_assignment.c.
1153 * the same thing for p++ where "p" is a struct. Most modifications
1154 * are handled by the assignment hook or the db. Smatch_extra.c doesn't
1155 * use smatch_modification.c because we have to get the ordering right
1156 * or something. So if you have p++ where p is a pointer to a standard
1157 * c type then we handle that here. What a mess.
1158 */
1159 expr = strip_expr(expr);
1160 type = get_type(expr);
1161 if (!type || type->type != SYM_PTR)
1162 return;
1163 type = get_real_base_type(type);
1164 if (!type || type->type != SYM_BASETYPE)
1165 return;
1166 set_extra_expr_nomod(deref_expression(expr), alloc_estate_whole(type));
1167 }
1168
1169 static void unop_expr(struct expression *expr)
1170 {
1171 struct smatch_state *state;
1172
1173 if (expr->smatch_flags & Handled)
1174 return;
1175
1176 switch (expr->op) {
1177 case SPECIAL_INCREMENT:
1178 state = get_state_expr(SMATCH_EXTRA, expr->unop);
1179 state = increment_state(state);
1180 if (!state)
1181 state = alloc_estate_whole(get_type(expr));
1182 set_extra_expr_mod(expr->unop, state);
1183 clear_pointed_at_state(expr->unop);
1184 break;
1185 case SPECIAL_DECREMENT:
1186 state = get_state_expr(SMATCH_EXTRA, expr->unop);
1187 state = decrement_state(state);
1188 if (!state)
1189 state = alloc_estate_whole(get_type(expr));
1190 set_extra_expr_mod(expr->unop, state);
1191 clear_pointed_at_state(expr->unop);
1192 break;
1193 default:
1194 return;
1195 }
1196 }
1197
1198 static void asm_expr(struct statement *stmt)
1199 {
1200
1201 struct expression *expr;
1202 struct symbol *type;
1203 int state = 0;
1204
1205 FOR_EACH_PTR(stmt->asm_outputs, expr) {
1206 switch (state) {
1207 case 0: /* identifier */
1208 case 1: /* constraint */
1209 state++;
1210 continue;
1211 case 2: /* expression */
1212 state = 0;
1213 type = get_type(strip_expr(expr));
1214 set_extra_expr_mod(expr, alloc_estate_whole(type));
1215 continue;
1216 }
1217 } END_FOR_EACH_PTR(expr);
1218 }
1219
1220 static void check_dereference(struct expression *expr)
1221 {
1222 struct smatch_state *state;
1223
1224 if (__in_fake_assign)
1225 return;
1226 if (outside_of_function())
1227 return;
1228 state = get_extra_state(expr);
1229 if (state) {
1230 struct range_list *rl;
1231
1232 rl = rl_intersection(estate_rl(state), valid_ptr_rl);
1233 if (rl_equiv(rl, estate_rl(state)))
1234 return;
1235 set_extra_expr_nomod(expr, alloc_estate_rl(rl));
1236 } else {
1237 set_extra_expr_nomod(expr, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
1238 }
1239 }
1240
1241 static void match_dereferences(struct expression *expr)
1242 {
1243 if (expr->type != EXPR_PREOP)
1244 return;
1245 /* it's saying that foo[1] = bar dereferences foo[1] */
1246 if (is_array(expr))
1247 return;
1248 check_dereference(expr->unop);
1249 }
1250
1251 static void match_pointer_as_array(struct expression *expr)
1252 {
1253 if (!is_array(expr))
1254 return;
1255 check_dereference(get_array_base(expr));
1256 }
1257
1258 static void find_dereferences(struct expression *expr)
1259 {
1260 while (expr->type == EXPR_PREOP) {
1261 if (expr->op == '*')
1262 check_dereference(expr->unop);
1263 expr = strip_expr(expr->unop);
1264 }
1265 }
1266
1267 static void set_param_dereferenced(struct expression *call, struct expression *arg, char *key, char *unused)
1268 {
1269 struct symbol *sym;
1270 char *name;
1271
1272 name = get_variable_from_key(arg, key, &sym);
1273 if (name && sym) {
1274 struct smatch_state *orig, *new;
1275 struct range_list *rl;
1276
1277 orig = get_state(SMATCH_EXTRA, name, sym);
1278 if (orig) {
1279 rl = rl_intersection(estate_rl(orig),
1280 alloc_rl(valid_ptr_min_sval,
1281 valid_ptr_max_sval));
1282 new = alloc_estate_rl(rl);
1283 } else {
1284 new = alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval);
1285 }
1286
1287 set_extra_nomod(name, sym, NULL, new);
1288 }
1289 free_string(name);
1290
1291 find_dereferences(arg);
1292 }
1293
1294 static sval_t add_one(sval_t sval)
1295 {
1296 sval.value++;
1297 return sval;
1298 }
1299
1300 static int handle_postop_inc(struct expression *left, int op, struct expression *right)
1301 {
1302 struct statement *stmt;
1303 struct expression *cond;
1304 struct smatch_state *true_state, *false_state;
1305 sval_t start;
1306 sval_t limit;
1307
1308 /*
1309 * If we're decrementing here then that's a canonical while count down
1310 * so it's handled already. We're only handling loops like:
1311 * i = 0;
1312 * do { ... } while (i++ < 3);
1313 */
1314
1315 if (left->type != EXPR_POSTOP || left->op != SPECIAL_INCREMENT)
1316 return 0;
1317
1318 stmt = __cur_stmt->parent;
1319 if (!stmt)
1320 return 0;
1321 if (stmt->type == STMT_COMPOUND)
1322 stmt = stmt->parent;
1323 if (!stmt || stmt->type != STMT_ITERATOR || !stmt->iterator_post_condition)
1324 return 0;
1325
1326 cond = strip_expr(stmt->iterator_post_condition);
1327 if (cond->type != EXPR_COMPARE || cond->op != op)
1328 return 0;
1329 if (left != strip_expr(cond->left) || right != strip_expr(cond->right))
1330 return 0;
1331
1332 if (!get_implied_value(left->unop, &start))
1333 return 0;
1334 if (!get_implied_value(right, &limit))
1335 return 0;
1336
1337 if (sval_cmp(start, limit) > 0)
1338 return 0;
1339
1340 switch (op) {
1341 case '<':
1342 case SPECIAL_UNSIGNED_LT:
1343 break;
1344 case SPECIAL_LTE:
1345 case SPECIAL_UNSIGNED_LTE:
1346 limit = add_one(limit);
1347 default:
1348 return 0;
1349
1350 }
1351
1352 true_state = alloc_estate_range(add_one(start), limit);
1353 false_state = alloc_estate_range(add_one(limit), add_one(limit));
1354
1355 /* Currently we just discard the false state but when two passes is
1356 * implimented correctly then it will use it.
1357 */
1358
1359 set_extra_expr_true_false(left->unop, true_state, false_state);
1360
1361 return 1;
1362 }
1363
1364 bool is_impossible_variable(struct expression *expr)
1365 {
1366 struct smatch_state *state;
1367
1368 state = get_extra_state(expr);
1369 if (state && !estate_rl(state))
1370 return true;
1371 return false;
1372 }
1373
1374 static void handle_comparison(struct symbol *type, struct expression *left, int op, struct expression *right)
1375 {
1376 struct range_list *left_orig;
1377 struct range_list *left_true;
1378 struct range_list *left_false;
1379 struct range_list *right_orig;
1380 struct range_list *right_true;
1381 struct range_list *right_false;
1382 struct smatch_state *left_true_state;
1383 struct smatch_state *left_false_state;
1384 struct smatch_state *right_true_state;
1385 struct smatch_state *right_false_state;
1386 sval_t dummy, hard_max;
1387 int left_postop = 0;
1388 int right_postop = 0;
1389
1390 if (left->op == SPECIAL_INCREMENT || left->op == SPECIAL_DECREMENT) {
1391 if (left->type == EXPR_POSTOP) {
1392 left->smatch_flags |= Handled;
1393 left_postop = left->op;
1394 if (handle_postop_inc(left, op, right))
1395 return;
1396 }
1397 left = strip_parens(left->unop);
1398 }
1399 while (left->type == EXPR_ASSIGNMENT)
1400 left = strip_parens(left->left);
1401
1402 if (right->op == SPECIAL_INCREMENT || right->op == SPECIAL_DECREMENT) {
1403 if (right->type == EXPR_POSTOP) {
1404 right->smatch_flags |= Handled;
1405 right_postop = right->op;
1406 }
1407 right = strip_parens(right->unop);
1408 }
1409
1410 if (is_impossible_variable(left) || is_impossible_variable(right))
1411 return;
1412
1413 get_real_absolute_rl(left, &left_orig);
1414 left_orig = cast_rl(type, left_orig);
1415
1416 get_real_absolute_rl(right, &right_orig);
1417 right_orig = cast_rl(type, right_orig);
1418
1419 split_comparison_rl(left_orig, op, right_orig, &left_true, &left_false, &right_true, &right_false);
1420
1421 left_true = rl_truncate_cast(get_type(strip_expr(left)), left_true);
1422 left_false = rl_truncate_cast(get_type(strip_expr(left)), left_false);
1423 right_true = rl_truncate_cast(get_type(strip_expr(right)), right_true);
1424 right_false = rl_truncate_cast(get_type(strip_expr(right)), right_false);
1425
1426 if (!left_true || !left_false) {
1427 struct range_list *tmp_true, *tmp_false;
1428
1429 split_comparison_rl(alloc_whole_rl(type), op, right_orig, &tmp_true, &tmp_false, NULL, NULL);
1430 tmp_true = rl_truncate_cast(get_type(strip_expr(left)), tmp_true);
1431 tmp_false = rl_truncate_cast(get_type(strip_expr(left)), tmp_false);
1432 if (tmp_true && tmp_false)
1433 __save_imaginary_state(left, tmp_true, tmp_false);
1434 }
1435
1436 if (!right_true || !right_false) {
1437 struct range_list *tmp_true, *tmp_false;
1438
1439 split_comparison_rl(alloc_whole_rl(type), op, right_orig, NULL, NULL, &tmp_true, &tmp_false);
1440 tmp_true = rl_truncate_cast(get_type(strip_expr(right)), tmp_true);
1441 tmp_false = rl_truncate_cast(get_type(strip_expr(right)), tmp_false);
1442 if (tmp_true && tmp_false)
1443 __save_imaginary_state(right, tmp_true, tmp_false);
1444 }
1445
1446 left_true_state = alloc_estate_rl(left_true);
1447 left_false_state = alloc_estate_rl(left_false);
1448 right_true_state = alloc_estate_rl(right_true);
1449 right_false_state = alloc_estate_rl(right_false);
1450
1451 switch (op) {
1452 case '<':
1453 case SPECIAL_UNSIGNED_LT:
1454 case SPECIAL_UNSIGNED_LTE:
1455 case SPECIAL_LTE:
1456 if (get_hard_max(right, &dummy))
1457 estate_set_hard_max(left_true_state);
1458 if (get_hard_max(left, &dummy))
1459 estate_set_hard_max(right_false_state);
1460 break;
1461 case '>':
1462 case SPECIAL_UNSIGNED_GT:
1463 case SPECIAL_UNSIGNED_GTE:
1464 case SPECIAL_GTE:
1465 if (get_hard_max(left, &dummy))
1466 estate_set_hard_max(right_true_state);
1467 if (get_hard_max(right, &dummy))
1468 estate_set_hard_max(left_false_state);
1469 break;
1470 }
1471
1472 switch (op) {
1473 case '<':
1474 case SPECIAL_UNSIGNED_LT:
1475 case SPECIAL_UNSIGNED_LTE:
1476 case SPECIAL_LTE:
1477 if (get_hard_max(right, &hard_max)) {
1478 if (op == '<' || op == SPECIAL_UNSIGNED_LT)
1479 hard_max.value--;
1480 estate_set_fuzzy_max(left_true_state, hard_max);
1481 }
1482 if (get_implied_value(right, &hard_max)) {
1483 if (op == SPECIAL_UNSIGNED_LTE ||
1484 op == SPECIAL_LTE)
1485 hard_max.value++;
1486 estate_set_fuzzy_max(left_false_state, hard_max);
1487 }
1488 if (get_hard_max(left, &hard_max)) {
1489 if (op == SPECIAL_UNSIGNED_LTE ||
1490 op == SPECIAL_LTE)
1491 hard_max.value--;
1492 estate_set_fuzzy_max(right_false_state, hard_max);
1493 }
1494 if (get_implied_value(left, &hard_max)) {
1495 if (op == '<' || op == SPECIAL_UNSIGNED_LT)
1496 hard_max.value++;
1497 estate_set_fuzzy_max(right_true_state, hard_max);
1498 }
1499 break;
1500 case '>':
1501 case SPECIAL_UNSIGNED_GT:
1502 case SPECIAL_UNSIGNED_GTE:
1503 case SPECIAL_GTE:
1504 if (get_hard_max(left, &hard_max)) {
1505 if (op == '>' || op == SPECIAL_UNSIGNED_GT)
1506 hard_max.value--;
1507 estate_set_fuzzy_max(right_true_state, hard_max);
1508 }
1509 if (get_implied_value(left, &hard_max)) {
1510 if (op == SPECIAL_UNSIGNED_GTE ||
1511 op == SPECIAL_GTE)
1512 hard_max.value++;
1513 estate_set_fuzzy_max(right_false_state, hard_max);
1514 }
1515 if (get_hard_max(right, &hard_max)) {
1516 if (op == SPECIAL_UNSIGNED_LTE ||
1517 op == SPECIAL_LTE)
1518 hard_max.value--;
1519 estate_set_fuzzy_max(left_false_state, hard_max);
1520 }
1521 if (get_implied_value(right, &hard_max)) {
1522 if (op == '>' ||
1523 op == SPECIAL_UNSIGNED_GT)
1524 hard_max.value++;
1525 estate_set_fuzzy_max(left_true_state, hard_max);
1526 }
1527 break;
1528 case SPECIAL_EQUAL:
1529 if (get_hard_max(left, &hard_max))
1530 estate_set_fuzzy_max(right_true_state, hard_max);
1531 if (get_hard_max(right, &hard_max))
1532 estate_set_fuzzy_max(left_true_state, hard_max);
1533 break;
1534 }
1535
1536 if (get_hard_max(left, &hard_max)) {
1537 estate_set_hard_max(left_true_state);
1538 estate_set_hard_max(left_false_state);
1539 }
1540 if (get_hard_max(right, &hard_max)) {
1541 estate_set_hard_max(right_true_state);
1542 estate_set_hard_max(right_false_state);
1543 }
1544
1545 if (left_postop == SPECIAL_INCREMENT) {
1546 left_true_state = increment_state(left_true_state);
1547 left_false_state = increment_state(left_false_state);
1548 }
1549 if (left_postop == SPECIAL_DECREMENT) {
1550 left_true_state = decrement_state(left_true_state);
1551 left_false_state = decrement_state(left_false_state);
1552 }
1553 if (right_postop == SPECIAL_INCREMENT) {
1554 right_true_state = increment_state(right_true_state);
1555 right_false_state = increment_state(right_false_state);
1556 }
1557 if (right_postop == SPECIAL_DECREMENT) {
1558 right_true_state = decrement_state(right_true_state);
1559 right_false_state = decrement_state(right_false_state);
1560 }
1561
1562 if (estate_rl(left_true_state) && estates_equiv(left_true_state, left_false_state)) {
1563 left_true_state = NULL;
1564 left_false_state = NULL;
1565 }
1566
1567 if (estate_rl(right_true_state) && estates_equiv(right_true_state, right_false_state)) {
1568 right_true_state = NULL;
1569 right_false_state = NULL;
1570 }
1571
1572 /* Don't introduce new states for known true/false conditions */
1573 if (rl_equiv(left_orig, estate_rl(left_true_state)))
1574 left_true_state = NULL;
1575 if (rl_equiv(left_orig, estate_rl(left_false_state)))
1576 left_false_state = NULL;
1577 if (rl_equiv(right_orig, estate_rl(right_true_state)))
1578 right_true_state = NULL;
1579 if (rl_equiv(right_orig, estate_rl(right_false_state)))
1580 right_false_state = NULL;
1581
1582 set_extra_expr_true_false(left, left_true_state, left_false_state);
1583 set_extra_expr_true_false(right, right_true_state, right_false_state);
1584 }
1585
1586 static int is_simple_math(struct expression *expr)
1587 {
1588 if (!expr)
1589 return 0;
1590 if (expr->type != EXPR_BINOP)
1591 return 0;
1592 switch (expr->op) {
1593 case '+':
1594 case '-':
1595 case '*':
1596 return 1;
1597 }
1598 return 0;
1599 }
1600
1601 static void move_known_values(struct expression **left_p, struct expression **right_p)
1602 {
1603 struct expression *left = *left_p;
1604 struct expression *right = *right_p;
1605 sval_t sval, dummy;
1606
1607 if (get_implied_value(left, &sval)) {
1608 if (!is_simple_math(right))
1609 return;
1610 if (get_implied_value(right, &dummy))
1611 return;
1612 if (right->op == '*') {
1613 sval_t divisor;
1614
1615 if (!get_value(right->right, &divisor))
1616 return;
1617 if (divisor.value == 0)
1618 return;
1619 *left_p = binop_expression(left, invert_op(right->op), right->right);
1620 *right_p = right->left;
1621 return;
1622 }
1623 if (right->op == '+' && get_value(right->left, &sval)) {
1624 *left_p = binop_expression(left, invert_op(right->op), right->left);
1625 *right_p = right->right;
1626 return;
1627 }
1628 if (get_value(right->right, &sval)) {
1629 *left_p = binop_expression(left, invert_op(right->op), right->right);
1630 *right_p = right->left;
1631 return;
1632 }
1633 return;
1634 }
1635 if (get_implied_value(right, &sval)) {
1636 if (!is_simple_math(left))
1637 return;
1638 if (get_implied_value(left, &dummy))
1639 return;
1640 if (left->op == '*') {
1641 sval_t divisor;
1642
1643 if (!get_value(left->right, &divisor))
1644 return;
1645 if (divisor.value == 0)
1646 return;
1647 *right_p = binop_expression(right, invert_op(left->op), left->right);
1648 *left_p = left->left;
1649 return;
1650 }
1651 if (left->op == '+' && get_value(left->left, &sval)) {
1652 *right_p = binop_expression(right, invert_op(left->op), left->left);
1653 *left_p = left->right;
1654 return;
1655 }
1656
1657 if (get_value(left->right, &sval)) {
1658 *right_p = binop_expression(right, invert_op(left->op), left->right);
1659 *left_p = left->left;
1660 return;
1661 }
1662 return;
1663 }
1664 }
1665
1666 /*
1667 * The reason for do_simple_algebra() is to solve things like:
1668 * if (foo > 66 || foo + bar > 64) {
1669 * "foo" is not really a known variable so it won't be handled by
1670 * move_known_variables() but it's a super common idiom.
1671 *
1672 */
1673 static int do_simple_algebra(struct expression **left_p, struct expression **right_p)
1674 {
1675 struct expression *left = *left_p;
1676 struct expression *right = *right_p;
1677 struct range_list *rl;
1678 sval_t tmp;
1679
1680 if (left->type != EXPR_BINOP || left->op != '+')
1681 return 0;
1682 if (can_integer_overflow(get_type(left), left))
1683 return 0;
1684 if (!get_implied_value(right, &tmp))
1685 return 0;
1686
1687 if (!get_implied_value(left->left, &tmp) &&
1688 get_implied_rl(left->left, &rl) &&
1689 !is_whole_rl(rl)) {
1690 *right_p = binop_expression(right, '-', left->left);
1691 *left_p = left->right;
1692 return 1;
1693 }
1694 if (!get_implied_value(left->right, &tmp) &&
1695 get_implied_rl(left->right, &rl) &&
1696 !is_whole_rl(rl)) {
1697 *right_p = binop_expression(right, '-', left->right);
1698 *left_p = left->left;
1699 return 1;
1700 }
1701
1702 return 0;
1703 }
1704
1705 static int match_func_comparison(struct expression *expr)
1706 {
1707 struct expression *left = strip_expr(expr->left);
1708 struct expression *right = strip_expr(expr->right);
1709 sval_t sval;
1710
1711 /*
1712 * fixme: think about this harder. We should always be trying to limit
1713 * the non-call side as well. If we can't determine the limitter does
1714 * that mean we aren't querying the database and are missing important
1715 * information?
1716 */
1717
1718 if (left->type == EXPR_CALL) {
1719 if (get_implied_value(left, &sval)) {
1720 handle_comparison(get_type(expr), left, expr->op, right);
1721 return 1;
1722 }
1723 function_comparison(left, expr->op, right);
1724 return 1;
1725 }
1726
1727 if (right->type == EXPR_CALL) {
1728 if (get_implied_value(right, &sval)) {
1729 handle_comparison(get_type(expr), left, expr->op, right);
1730 return 1;
1731 }
1732 function_comparison(left, expr->op, right);
1733 return 1;
1734 }
1735
1736 return 0;
1737 }
1738
1739 /* Handle conditions like "if (foo + bar < foo) {" */
1740 static int handle_integer_overflow_test(struct expression *expr)
1741 {
1742 struct expression *left, *right;
1743 struct symbol *type;
1744 sval_t left_min, right_min, min, max;
1745
1746 if (expr->op != '<' && expr->op != SPECIAL_UNSIGNED_LT)
1747 return 0;
1748
1749 left = strip_parens(expr->left);
1750 right = strip_parens(expr->right);
1751
1752 if (left->op != '+')
1753 return 0;
1754
1755 type = get_type(expr);
1756 if (!type)
1757 return 0;
1758 if (type_positive_bits(type) == 32) {
1759 max.type = &uint_ctype;
1760 max.uvalue = (unsigned int)-1;
1761 } else if (type_positive_bits(type) == 64) {
1762 max.type = &ulong_ctype;
1763 max.value = (unsigned long long)-1;
1764 } else {
1765 return 0;
1766 }
1767
1768 if (!expr_equiv(left->left, right) && !expr_equiv(left->right, right))
1769 return 0;
1770
1771 get_absolute_min(left->left, &left_min);
1772 get_absolute_min(left->right, &right_min);
1773 min = sval_binop(left_min, '+', right_min);
1774
1775 set_extra_chunk_true_false(left, NULL, alloc_estate_range(min, max));
1776 return 1;
1777 }
1778
1779 static void match_comparison(struct expression *expr)
1780 {
1781 struct expression *left_orig = strip_parens(expr->left);
1782 struct expression *right_orig = strip_parens(expr->right);
1783 struct expression *left, *right, *tmp;
1784 struct expression *prev;
1785 struct symbol *type;
1786 int redo, count;
1787
1788 if (match_func_comparison(expr))
1789 return;
1790
1791 type = get_type(expr);
1792 if (!type)
1793 type = &llong_ctype;
1794
1795 if (handle_integer_overflow_test(expr))
1796 return;
1797
1798 left = left_orig;
1799 right = right_orig;
1800 move_known_values(&left, &right);
1801 handle_comparison(type, left, expr->op, right);
1802
1803 left = left_orig;
1804 right = right_orig;
1805 if (do_simple_algebra(&left, &right))
1806 handle_comparison(type, left, expr->op, right);
1807
1808 prev = get_assigned_expr(left_orig);
1809 if (is_simple_math(prev) && has_variable(prev, left_orig) == 0) {
1810 left = prev;
1811 right = right_orig;
1812 move_known_values(&left, &right);
1813 handle_comparison(type, left, expr->op, right);
1814 }
1815
1816 prev = get_assigned_expr(right_orig);
1817 if (is_simple_math(prev) && has_variable(prev, right_orig) == 0) {
1818 left = left_orig;
1819 right = prev;
1820 move_known_values(&left, &right);
1821 handle_comparison(type, left, expr->op, right);
1822 }
1823
1824 redo = 0;
1825 left = left_orig;
1826 right = right_orig;
1827 if (get_last_expr_from_expression_stmt(left_orig)) {
1828 left = get_last_expr_from_expression_stmt(left_orig);
1829 redo = 1;
1830 }
1831 if (get_last_expr_from_expression_stmt(right_orig)) {
1832 right = get_last_expr_from_expression_stmt(right_orig);
1833 redo = 1;
1834 }
1835
1836 if (!redo)
1837 return;
1838
1839 count = 0;
1840 while ((tmp = get_assigned_expr(left))) {
1841 if (count++ > 3)
1842 break;
1843 left = strip_expr(tmp);
1844 }
1845 count = 0;
1846 while ((tmp = get_assigned_expr(right))) {
1847 if (count++ > 3)
1848 break;
1849 right = strip_expr(tmp);
1850 }
1851
1852 handle_comparison(type, left, expr->op, right);
1853 }
1854
1855 static sval_t get_high_mask(sval_t known)
1856 {
1857 sval_t ret;
1858 int i;
1859
1860 ret = known;
1861 ret.value = 0;
1862
1863 for (i = type_bits(known.type) - 1; i >= 0; i--) {
1864 if (known.uvalue & (1ULL << i))
1865 ret.uvalue |= (1ULL << i);
1866 else
1867 return ret;
1868
1869 }
1870 return ret;
1871 }
1872
1873 static void handle_AND_op(struct expression *var, sval_t known)
1874 {
1875 struct range_list *orig_rl;
1876 struct range_list *true_rl = NULL;
1877 struct range_list *false_rl = NULL;
1878 int bit;
1879 sval_t low_mask = known;
1880 sval_t high_mask;
1881 sval_t max;
1882
1883 get_absolute_rl(var, &orig_rl);
1884
1885 if (known.value > 0) {
1886 bit = ffsll(known.value) - 1;
1887 low_mask.uvalue = (1ULL << bit) - 1;
1888 true_rl = remove_range(orig_rl, sval_type_val(known.type, 0), low_mask);
1889 }
1890 high_mask = get_high_mask(known);
1891 if (high_mask.value) {
1892 bit = ffsll(high_mask.value) - 1;
1893 low_mask.uvalue = (1ULL << bit) - 1;
1894
1895 false_rl = orig_rl;
1896 if (sval_is_negative(rl_min(orig_rl)))
1897 false_rl = remove_range(false_rl, sval_type_min(known.type), sval_type_val(known.type, -1));
1898 false_rl = remove_range(false_rl, low_mask, sval_type_max(known.type));
1899 if (type_signed(high_mask.type) && type_unsigned(rl_type(false_rl))) {
1900 false_rl = remove_range(false_rl,
1901 sval_type_val(rl_type(false_rl), sval_type_max(known.type).uvalue),
1902 sval_type_val(rl_type(false_rl), -1));
1903 }
1904 } else if (known.value == 1 &&
1905 get_hard_max(var, &max) &&
1906 sval_cmp(max, rl_max(orig_rl)) == 0 &&
1907 max.value & 1) {
1908 false_rl = remove_range(orig_rl, max, max);
1909 }
1910 set_extra_expr_true_false(var,
1911 true_rl ? alloc_estate_rl(true_rl) : NULL,
1912 false_rl ? alloc_estate_rl(false_rl) : NULL);
1913 }
1914
1915 static void handle_AND_condition(struct expression *expr)
1916 {
1917 sval_t known;
1918
1919 if (get_implied_value(expr->left, &known))
1920 handle_AND_op(expr->right, known);
1921 else if (get_implied_value(expr->right, &known))
1922 handle_AND_op(expr->left, known);
1923 }
1924
1925 static void handle_MOD_condition(struct expression *expr)
1926 {
1927 struct range_list *orig_rl;
1928 struct range_list *true_rl;
1929 struct range_list *false_rl = NULL;
1930 sval_t right;
1931 sval_t zero = {
1932 .value = 0,
1933 };
1934
1935 if (!get_implied_value(expr->right, &right) || right.value == 0)
1936 return;
1937 get_absolute_rl(expr->left, &orig_rl);
1938
1939 zero.type = rl_type(orig_rl);
1940
1941 /* We're basically dorking around the min and max here */
1942 true_rl = remove_range(orig_rl, zero, zero);
1943 if (!sval_is_max(rl_max(true_rl)) &&
1944 !(rl_max(true_rl).value % right.value))
1945 true_rl = remove_range(true_rl, rl_max(true_rl), rl_max(true_rl));
1946
1947 if (rl_equiv(true_rl, orig_rl))
1948 true_rl = NULL;
1949
1950 if (sval_is_positive(rl_min(orig_rl)) &&
1951 (rl_max(orig_rl).value - rl_min(orig_rl).value) / right.value < 5) {
1952 sval_t add;
1953 int i;
1954
1955 add = rl_min(orig_rl);
1956 add.value += right.value - (add.value % right.value);
1957 add.value -= right.value;
1958
1959 for (i = 0; i < 5; i++) {
1960 add.value += right.value;
1961 if (add.value > rl_max(orig_rl).value)
1962 break;
1963 add_range(&false_rl, add, add);
1964 }
1965 } else {
1966 if (rl_min(orig_rl).uvalue != 0 &&
1967 rl_min(orig_rl).uvalue < right.uvalue) {
1968 sval_t chop = right;
1969 chop.value--;
1970 false_rl = remove_range(orig_rl, zero, chop);
1971 }
1972
1973 if (!sval_is_max(rl_max(orig_rl)) &&
1974 (rl_max(orig_rl).value % right.value)) {
1975 sval_t chop = rl_max(orig_rl);
1976 chop.value -= chop.value % right.value;
1977 chop.value++;
1978 if (!false_rl)
1979 false_rl = clone_rl(orig_rl);
1980 false_rl = remove_range(false_rl, chop, rl_max(orig_rl));
1981 }
1982 }
1983
1984 set_extra_expr_true_false(expr->left,
1985 true_rl ? alloc_estate_rl(true_rl) : NULL,
1986 false_rl ? alloc_estate_rl(false_rl) : NULL);
1987 }
1988
1989 /* this is actually hooked from smatch_implied.c... it's hacky, yes */
1990 void __extra_match_condition(struct expression *expr)
1991 {
1992 struct smatch_state *pre_state;
1993 struct smatch_state *true_state;
1994 struct smatch_state *false_state;
1995 struct range_list *pre_rl;
1996
1997 expr = strip_expr(expr);
1998 switch (expr->type) {
1999 case EXPR_CALL:
2000 function_comparison(expr, SPECIAL_NOTEQUAL, zero_expr());
2001 return;
2002 case EXPR_PREOP:
2003 case EXPR_SYMBOL:
2004 case EXPR_DEREF: {
2005 sval_t zero;
2006
2007 zero = sval_blank(expr);
2008 zero.value = 0;
2009
2010 pre_state = get_extra_state(expr);
2011 if (estate_is_empty(pre_state))
2012 return;
2013 if (pre_state)
2014 pre_rl = estate_rl(pre_state);
2015 else
2016 get_absolute_rl(expr, &pre_rl);
2017 if (possibly_true_rl(pre_rl, SPECIAL_EQUAL, rl_zero()))
2018 false_state = alloc_estate_sval(zero);
2019 else
2020 false_state = alloc_estate_empty();
2021 true_state = alloc_estate_rl(remove_range(pre_rl, zero, zero));
2022 set_extra_expr_true_false(expr, true_state, false_state);
2023 return;
2024 }
2025 case EXPR_COMPARE:
2026 match_comparison(expr);
2027 return;
2028 case EXPR_ASSIGNMENT:
2029 __extra_match_condition(expr->left);
2030 return;
2031 case EXPR_BINOP:
2032 if (expr->op == '&')
2033 handle_AND_condition(expr);
2034 if (expr->op == '%')
2035 handle_MOD_condition(expr);
2036 return;
2037 }
2038 }
2039
2040 static void assume_indexes_are_valid(struct expression *expr)
2041 {
2042 struct expression *array_expr;
2043 int array_size;
2044 struct expression *offset;
2045 struct symbol *offset_type;
2046 struct range_list *rl_before;
2047 struct range_list *rl_after;
2048 struct range_list *filter = NULL;
2049 sval_t size;
2050
2051 expr = strip_expr(expr);
2052 if (!is_array(expr))
2053 return;
2054
2055 offset = get_array_offset(expr);
2056 offset_type = get_type(offset);
2057 if (offset_type && type_signed(offset_type)) {
2058 filter = alloc_rl(sval_type_min(offset_type),
2059 sval_type_val(offset_type, -1));
2060 }
2061
2062 array_expr = get_array_base(expr);
2063 array_size = get_real_array_size(array_expr);
2064 if (array_size > 1) {
2065 size = sval_type_val(offset_type, array_size);
2066 add_range(&filter, size, sval_type_max(offset_type));
2067 }
2068
2069 if (!filter)
2070 return;
2071 get_absolute_rl(offset, &rl_before);
2072 rl_after = rl_filter(rl_before, filter);
2073 if (rl_equiv(rl_before, rl_after))
2074 return;
2075 set_extra_expr_nomod(offset, alloc_estate_rl(rl_after));
2076 }
2077
2078 /* returns 1 if it is not possible for expr to be value, otherwise returns 0 */
2079 int implied_not_equal(struct expression *expr, long long val)
2080 {
2081 return !possibly_false(expr, SPECIAL_NOTEQUAL, value_expr(val));
2082 }
2083
2084 int implied_not_equal_name_sym(char *name, struct symbol *sym, long long val)
2085 {
2086 struct smatch_state *estate;
2087
2088 estate = get_state(SMATCH_EXTRA, name, sym);
2089 if (!estate)
2090 return 0;
2091 if (!rl_has_sval(estate_rl(estate), sval_type_val(estate_type(estate), 0)))
2092 return 1;
2093 return 0;
2094 }
2095
2096 int parent_is_null_var_sym(const char *name, struct symbol *sym)
2097 {
2098 char buf[256];
2099 char *start;
2100 char *end;
2101 struct smatch_state *state;
2102
2103 strncpy(buf, name, sizeof(buf) - 1);
2104 buf[sizeof(buf) - 1] = '\0';
2105
2106 start = &buf[0];
2107 while (*start == '*') {
2108 start++;
2109 state = get_state(SMATCH_EXTRA, start, sym);
2110 if (!state)
2111 continue;
2112 if (!estate_rl(state))
2113 return 1;
2114 if (estate_min(state).value == 0 &&
2115 estate_max(state).value == 0)
2116 return 1;
2117 }
2118
2119 start = &buf[0];
2120 while (*start == '&')
2121 start++;
2122
2123 while ((end = strrchr(start, '-'))) {
2124 *end = '\0';
2125 state = __get_state(SMATCH_EXTRA, start, sym);
2126 if (!state)
2127 continue;
2128 if (estate_min(state).value == 0 &&
2129 estate_max(state).value == 0)
2130 return 1;
2131 }
2132 return 0;
2133 }
2134
2135 int parent_is_null(struct expression *expr)
2136 {
2137 struct symbol *sym;
2138 char *var;
2139 int ret = 0;
2140
2141 expr = strip_expr(expr);
2142 var = expr_to_var_sym(expr, &sym);
2143 if (!var || !sym)
2144 goto free;
2145 ret = parent_is_null_var_sym(var, sym);
2146 free:
2147 free_string(var);
2148 return ret;
2149 }
2150
2151 static int param_used_callback(void *found, int argc, char **argv, char **azColName)
2152 {
2153 *(int *)found = 1;
2154 return 0;
2155 }
2156
2157 static int filter_unused_kzalloc_info(struct expression *call, int param, char *printed_name, struct sm_state *sm)
2158 {
2159 sval_t sval;
2160 int found = 0;
2161
2162 /* for function pointers assume everything is used */
2163 if (call->fn->type != EXPR_SYMBOL)
2164 return 0;
2165
2166 /*
2167 * kzalloc() information is treated as special because so there is just
2168 * a lot of stuff initialized to zero and it makes building the database
2169 * take hours and hours.
2170 *
2171 * In theory, we should just remove this line and not pass any unused
2172 * information, but I'm not sure enough that this code works so I want
2173 * to hold off on that for now.
2174 */
2175 if (!estate_get_single_value(sm->state, &sval) || sval.value != 0)
2176 return 0;
2177
2178 run_sql(&param_used_callback, &found,
2179 "select * from return_implies where %s and type = %d and parameter = %d and key = '%s';",
2180 get_static_filter(call->fn->symbol), PARAM_USED, param, printed_name);
2181 if (found)
2182 return 0;
2183
2184 /* If the database is not built yet, then assume everything is used */
2185 run_sql(&param_used_callback, &found,
2186 "select * from return_implies where %s and type = %d;",
2187 get_static_filter(call->fn->symbol), PARAM_USED);
2188 if (!found)
2189 return 0;
2190
2191 return 1;
2192 }
2193
2194 struct range_list *intersect_with_real_abs_var_sym(const char *name, struct symbol *sym, struct range_list *start)
2195 {
2196 struct smatch_state *state;
2197
2198 /*
2199 * Here is the difference between implied value and real absolute, say
2200 * you have:
2201 *
2202 * int a = (u8)x;
2203 *
2204 * Then you know that a is 0-255. That's real absolute. But you don't
2205 * know for sure that it actually goes up to 255. So it's not implied.
2206 * Implied indicates a degree of certainty.
2207 *
2208 * But then say you cap "a" at 8. That means you know it goes up to
2209 * 8. So now the implied value is s32min-8. But you can combine it
2210 * with the real absolute to say that actually it's 0-8.
2211 *
2212 * We are combining it here. But now that I think about it, this is
2213 * probably not the ideal place to combine it because it should proably
2214 * be done earlier. Oh well, this is an improvement on what was there
2215 * before so I'm going to commit this code.
2216 *
2217 */
2218
2219 state = get_real_absolute_state_var_sym(name, sym);
2220 if (!state || !estate_rl(state))
2221 return start;
2222
2223 return rl_intersection(estate_rl(state), start);
2224 }
2225
2226 struct range_list *intersect_with_real_abs_expr(struct expression *expr, struct range_list *start)
2227 {
2228 struct smatch_state *state;
2229 struct range_list *abs_rl;
2230
2231 state = get_real_absolute_state(expr);
2232 if (!state || !estate_rl(state))
2233 return start;
2234
2235 abs_rl = cast_rl(rl_type(start), estate_rl(state));
2236 return rl_intersection(abs_rl, start);
2237 }
2238
2239 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
2240 {
2241 struct range_list *rl;
2242
2243 if (estate_is_whole(sm->state))
2244 return;
2245 if (filter_unused_kzalloc_info(call, param, printed_name, sm))
2246 return;
2247 rl = estate_rl(sm->state);
2248 rl = intersect_with_real_abs_var_sym(sm->name, sm->sym, rl);
2249 sql_insert_caller_info(call, PARAM_VALUE, param, printed_name, show_rl(rl));
2250 if (estate_has_fuzzy_max(sm->state))
2251 sql_insert_caller_info(call, FUZZY_MAX, param, printed_name,
2252 sval_to_str(estate_get_fuzzy_max(sm->state)));
2253 }
2254
2255 static void returned_struct_members(int return_id, char *return_ranges, struct expression *expr)
2256 {
2257 struct symbol *returned_sym;
2258 struct sm_state *sm;
2259 const char *param_name;
2260 char *compare_str;
2261 char buf[256];
2262
2263 returned_sym = expr_to_sym(expr);
2264 if (!returned_sym)
2265 return;
2266
2267 FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
2268 if (!estate_rl(sm->state))
2269 continue;
2270 if (returned_sym != sm->sym)
2271 continue;
2272
2273 param_name = get_param_name(sm);
2274 if (!param_name)
2275 continue;
2276 if (strcmp(param_name, "$") == 0)
2277 continue;
2278 compare_str = name_sym_to_param_comparison(sm->name, sm->sym);
2279 if (!compare_str && estate_is_whole(sm->state))
2280 continue;
2281 snprintf(buf, sizeof(buf), "%s%s", sm->state->name, compare_str ?: "");
2282
2283 sql_insert_return_states(return_id, return_ranges, PARAM_VALUE,
2284 -1, param_name, buf);
2285 } END_FOR_EACH_SM(sm);
2286 }
2287
2288 static void db_limited_before(void)
2289 {
2290 unmatched_stree = clone_stree(__get_cur_stree());
2291 }
2292
2293 static void db_limited_after(void)
2294 {
2295 free_stree(&unmatched_stree);
2296 }
2297
2298 static int rl_fits_in_type(struct range_list *rl, struct symbol *type)
2299 {
2300 if (type_bits(rl_type(rl)) <= type_bits(type))
2301 return 1;
2302 if (sval_cmp(rl_max(rl), sval_type_max(type)) > 0)
2303 return 0;
2304 if (sval_is_negative(rl_min(rl)) &&
2305 sval_cmp(rl_min(rl), sval_type_min(type)) < 0)
2306 return 0;
2307 return 1;
2308 }
2309
2310 static int basically_the_same(struct range_list *orig, struct range_list *new)
2311 {
2312 if (rl_equiv(orig, new))
2313 return 1;
2314
2315 /*
2316 * The whole range is essentially the same as 0,4096-27777777777 so
2317 * don't overwrite the implications just to store that.
2318 *
2319 */
2320 if (rl_type(orig)->type == SYM_PTR &&
2321 is_whole_rl(orig) &&
2322 rl_min(new).value == 0 &&
2323 rl_max(new).value == valid_ptr_max)
2324 return 1;
2325 return 0;
2326 }
2327
2328 static void db_param_limit_binops(struct expression *arg, char *key, struct range_list *rl)
2329 {
2330 struct range_list *left_rl;
2331 sval_t zero = { .type = rl_type(rl), };
2332 sval_t sval;
2333
2334 if (arg->op != '*')
2335 return;
2336 if (!get_implied_value(arg->right, &sval))
2337 return;
2338 if (can_integer_overflow(get_type(arg), arg))
2339 return;
2340
2341 left_rl = rl_binop(rl, '/', alloc_rl(sval, sval));
2342 if (!rl_has_sval(rl, zero))
2343 left_rl = remove_range(left_rl, zero, zero);
2344
2345 set_extra_expr_nomod(arg->left, alloc_estate_rl(left_rl));
2346 }
2347
2348 static void db_param_limit_filter(struct expression *expr, int param, char *key, char *value, enum info_type op)
2349 {
2350 struct expression *arg;
2351 char *name;
2352 struct symbol *sym;
2353 struct var_sym_list *vsl = NULL;
2354 struct sm_state *sm;
2355 struct symbol *compare_type, *var_type;
2356 struct range_list *rl;
2357 struct range_list *limit;
2358 struct range_list *new;
2359 char *tmp_name;
2360 struct symbol *tmp_sym;
2361
2362 while (expr->type == EXPR_ASSIGNMENT)
2363 expr = strip_expr(expr->right);
2364 if (expr->type != EXPR_CALL)
2365 return;
2366
2367 arg = get_argument_from_call_expr(expr->args, param);
2368 if (!arg)
2369 return;
2370
2371 name = get_chunk_from_key(arg, key, &sym, &vsl);
2372 if (!name)
2373 return;
2374 if (op != PARAM_LIMIT && !sym)
2375 goto free;
2376
2377 if (strcmp(key, "$") == 0)
2378 compare_type = get_arg_type(expr->fn, param);
2379 else
2380 compare_type = get_member_type_from_key(arg, key);
2381
2382 sm = get_sm_state(SMATCH_EXTRA, name, sym);
2383 if (sm)
2384 rl = estate_rl(sm->state);
2385 else
2386 rl = alloc_whole_rl(compare_type);
2387
2388 if (op == PARAM_LIMIT && !rl_fits_in_type(rl, compare_type))
2389 goto free;
2390
2391 call_results_to_rl(expr, compare_type, value, &limit);
2392 new = rl_intersection(rl, limit);
2393
2394 var_type = get_member_type_from_key(arg, key);
2395 new = cast_rl(var_type, new);
2396
2397 /* We want to preserve the implications here */
2398 if (sm && basically_the_same(estate_rl(sm->state), new))
2399 goto free;
2400 tmp_name = map_long_to_short_name_sym(name, sym, &tmp_sym);
2401 if (tmp_name && tmp_sym) {
2402 free_string(name);
2403 name = tmp_name;
2404 sym = tmp_sym;
2405 }
2406
2407 if (op == PARAM_LIMIT)
2408 set_extra_nomod_vsl(name, sym, vsl, NULL, alloc_estate_rl(new));
2409 else
2410 set_extra_mod(name, sym, NULL, alloc_estate_rl(new));
2411
2412 if (op == PARAM_LIMIT && arg->type == EXPR_BINOP)
2413 db_param_limit_binops(arg, key, new);
2414 free:
2415 free_string(name);
2416 }
2417
2418 static void db_param_limit(struct expression *expr, int param, char *key, char *value)
2419 {
2420 db_param_limit_filter(expr, param, key, value, PARAM_LIMIT);
2421 }
2422
2423 static void db_param_filter(struct expression *expr, int param, char *key, char *value)
2424 {
2425 db_param_limit_filter(expr, param, key, value, PARAM_FILTER);
2426 }
2427
2428 static void db_param_add_set(struct expression *expr, int param, char *key, char *value, enum info_type op)
2429 {
2430 struct expression *arg;
2431 char *name, *tmp_name;
2432 struct symbol *sym, *tmp_sym;
2433 struct symbol *param_type, *arg_type;
2434 struct smatch_state *state;
2435 struct range_list *new = NULL;
2436 struct range_list *added = NULL;
2437
2438 while (expr->type == EXPR_ASSIGNMENT)
2439 expr = strip_expr(expr->right);
2440 if (expr->type != EXPR_CALL)
2441 return;
2442
2443 arg = get_argument_from_call_expr(expr->args, param);
2444 if (!arg)
2445 return;
2446
2447 arg_type = get_arg_type_from_key(expr->fn, param, arg, key);
2448 param_type = get_member_type_from_key(arg, key);
2449 name = get_variable_from_key(arg, key, &sym);
2450 if (!name || !sym)
2451 goto free;
2452
2453 state = get_state(SMATCH_EXTRA, name, sym);
2454 if (state)
2455 new = estate_rl(state);
2456
2457 call_results_to_rl(expr, arg_type, value, &added);
2458 added = cast_rl(param_type, added);
2459 if (op == PARAM_SET)
2460 new = added;
2461 else
2462 new = rl_union(new, added);
2463
2464 tmp_name = map_long_to_short_name_sym_nostack(name, sym, &tmp_sym);
2465 if (tmp_name && tmp_sym) {
2466 free_string(name);
2467 name = tmp_name;
2468 sym = tmp_sym;
2469 }
2470 set_extra_mod(name, sym, NULL, alloc_estate_rl(new));
2471 free:
2472 free_string(name);
2473 }
2474
2475 static void db_param_add(struct expression *expr, int param, char *key, char *value)
2476 {
2477 in_param_set = true;
2478 db_param_add_set(expr, param, key, value, PARAM_ADD);
2479 in_param_set = false;
2480 }
2481
2482 static void db_param_set(struct expression *expr, int param, char *key, char *value)
2483 {
2484 in_param_set = true;
2485 db_param_add_set(expr, param, key, value, PARAM_SET);
2486 in_param_set = false;
2487 }
2488
2489 static void db_param_value(struct expression *expr, int param, char *key, char *value)
2490 {
2491 struct expression *call;
2492 char *name;
2493 struct symbol *sym;
2494 struct symbol *type;
2495 struct range_list *rl = NULL;
2496
2497 if (param != -1)
2498 return;
2499
2500 call = expr;
2501 while (call->type == EXPR_ASSIGNMENT)
2502 call = strip_expr(call->right);
2503 if (call->type != EXPR_CALL)
2504 return;
2505
2506 type = get_member_type_from_key(expr->left, key);
2507 name = get_variable_from_key(expr->left, key, &sym);
2508 if (!name || !sym)
2509 goto free;
2510
2511 call_results_to_rl(call, type, value, &rl);
2512
2513 set_extra_mod(name, sym, NULL, alloc_estate_rl(rl));
2514 free:
2515 free_string(name);
2516 }
2517
2518 static void match_call_info(struct expression *expr)
2519 {
2520 struct smatch_state *state;
2521 struct range_list *rl = NULL;
2522 struct expression *arg;
2523 struct symbol *type;
2524 int i = 0;
2525
2526 FOR_EACH_PTR(expr->args, arg) {
2527 type = get_arg_type(expr->fn, i);
2528
2529 get_absolute_rl(arg, &rl);
2530 rl = cast_rl(type, rl);
2531
2532 if (!is_whole_rl(rl)) {
2533 rl = intersect_with_real_abs_expr(arg, rl);
2534 sql_insert_caller_info(expr, PARAM_VALUE, i, "$", show_rl(rl));
2535 }
2536 state = get_state_expr(SMATCH_EXTRA, arg);
2537 if (estate_has_fuzzy_max(state)) {
2538 sql_insert_caller_info(expr, FUZZY_MAX, i, "$",
2539 sval_to_str(estate_get_fuzzy_max(state)));
2540 }
2541 i++;
2542 } END_FOR_EACH_PTR(arg);
2543 }
2544
2545 static void set_param_value(const char *name, struct symbol *sym, char *key, char *value)
2546 {
2547 struct range_list *rl = NULL;
2548 struct smatch_state *state;
2549 struct symbol *type;
2550 char fullname[256];
2551 sval_t dummy;
2552
2553 if (strcmp(key, "*$") == 0)
2554 snprintf(fullname, sizeof(fullname), "*%s", name);
2555 else if (strncmp(key, "$", 1) == 0)
2556 snprintf(fullname, 256, "%s%s", name, key + 1);
2557 else
2558 return;
2559
2560 type = get_member_type_from_key(symbol_expression(sym), key);
2561 str_to_rl(type, value, &rl);
2562 state = alloc_estate_rl(rl);
2563 if (estate_get_single_value(state, &dummy))
2564 estate_set_hard_max(state);
2565 set_state(SMATCH_EXTRA, fullname, sym, state);
2566 }
2567
2568 static void set_param_hard_max(const char *name, struct symbol *sym, char *key, char *value)
2569 {
2570 struct range_list *rl = NULL;
2571 struct smatch_state *state;
2572 struct symbol *type;
2573 char fullname[256];
2574 sval_t max;
2575
2576 if (strcmp(key, "*$") == 0)
2577 snprintf(fullname, sizeof(fullname), "*%s", name);
2578 else if (strncmp(key, "$", 1) == 0)
2579 snprintf(fullname, 256, "%s%s", name, key + 1);
2580 else
2581 return;
2582
2583 state = get_state(SMATCH_EXTRA, fullname, sym);
2584 if (!state)
2585 return;
2586 type = get_member_type_from_key(symbol_expression(sym), key);
2587 str_to_rl(type, value, &rl);
2588 if (!rl_to_sval(rl, &max))
2589 return;
2590 estate_set_fuzzy_max(state, max);
2591 }
2592
2593 struct sm_state *get_extra_sm_state(struct expression *expr)
2594 {
2595 char *name;
2596 struct symbol *sym;
2597 struct sm_state *ret = NULL;
2598
2599 name = expr_to_known_chunk_sym(expr, &sym);
2600 if (!name)
2601 goto free;
2602
2603 ret = get_sm_state(SMATCH_EXTRA, name, sym);
2604 free:
2605 free_string(name);
2606 return ret;
2607 }
2608
2609 struct smatch_state *get_extra_state(struct expression *expr)
2610 {
2611 struct sm_state *sm;
2612
2613 sm = get_extra_sm_state(expr);
2614 if (!sm)
2615 return NULL;
2616 return sm->state;
2617 }
2618
2619 void register_smatch_extra(int id)
2620 {
2621 my_id = id;
2622
2623 add_merge_hook(my_id, &merge_estates);
2624 add_unmatched_state_hook(my_id, &unmatched_state);
2625 select_caller_info_hook(set_param_value, PARAM_VALUE);
2626 select_caller_info_hook(set_param_hard_max, FUZZY_MAX);
2627 select_return_states_before(&db_limited_before);
2628 select_return_states_hook(PARAM_LIMIT, &db_param_limit);
2629 select_return_states_hook(PARAM_FILTER, &db_param_filter);
2630 select_return_states_hook(PARAM_ADD, &db_param_add);
2631 select_return_states_hook(PARAM_SET, &db_param_set);
2632 select_return_states_hook(PARAM_VALUE, &db_param_value);
2633 select_return_states_after(&db_limited_after);
2634 }
2635
2636 static void match_link_modify(struct sm_state *sm, struct expression *mod_expr)
2637 {
2638 struct var_sym_list *links;
2639 struct var_sym *tmp;
2640 struct smatch_state *state;
2641
2642 links = sm->state->data;
2643
2644 FOR_EACH_PTR(links, tmp) {
2645 if (sm->sym == tmp->sym &&
2646 strcmp(sm->name, tmp->var) == 0)
2647 continue;
2648 state = get_state(SMATCH_EXTRA, tmp->var, tmp->sym);
2649 if (!state)
2650 continue;
2651 set_state(SMATCH_EXTRA, tmp->var, tmp->sym, alloc_estate_whole(estate_type(state)));
2652 } END_FOR_EACH_PTR(tmp);
2653 set_state(link_id, sm->name, sm->sym, &undefined);
2654 }
2655
2656 void register_smatch_extra_links(int id)
2657 {
2658 link_id = id;
2659 }
2660
2661 void register_smatch_extra_late(int id)
2662 {
2663 add_merge_hook(link_id, &merge_link_states);
2664 add_modification_hook(link_id, &match_link_modify);
2665 add_hook(&match_dereferences, DEREF_HOOK);
2666 add_hook(&match_pointer_as_array, OP_HOOK);
2667 select_return_implies_hook(DEREFERENCE, &set_param_dereferenced);
2668 add_hook(&match_function_call, FUNCTION_CALL_HOOK);
2669 add_hook(&match_assign, ASSIGNMENT_HOOK);
2670 add_hook(&match_assign, GLOBAL_ASSIGNMENT_HOOK);
2671 add_hook(&unop_expr, OP_HOOK);
2672 add_hook(&asm_expr, ASM_HOOK);
2673
2674 add_hook(&match_call_info, FUNCTION_CALL_HOOK);
2675 add_member_info_callback(my_id, struct_member_callback);
2676 add_split_return_callback(&returned_struct_members);
2677
2678 // add_hook(&assume_indexes_are_valid, OP_HOOK);
2679 }
Static analysis for C