smatch_buf_comparison.c

   1 /*
   2  * Copyright (C) 2012 Oracle.
   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  * The point here is to store that a buffer has x bytes even if we don't know
  20  * the value of x.
  21  *
  22  */
  23
  24 #include "smatch.h"
  25 #include "smatch_extra.h"
  26 #include "smatch_slist.h"
  27
  28 static int size_id;
  29 static int link_id;
  30
  31 /*
  32  * There is a bunch of code which does this:
  33  *
  34  *     if (size)
  35  *         foo = malloc(size);
  36  *
  37  * So if "size" is non-zero then the size of "foo" is size.  But really it's
  38  * also true if size is zero.  It's just better to assume to not trample over
  39  * the data that we have by merging &undefined states.
  40  *
  41  */
  42 static struct smatch_state *unmatched_state(struct sm_state *sm)
  43 {
  44         return sm->state;
  45 }
  46
  47 static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
  48 {
  49         struct expression *expr1, *expr2;
  50
  51         expr1 = s1->data;
  52         expr2 = s2->data;
  53
  54         if (expr1 && expr2 && expr_equiv(expr1, expr2))
  55                 return s1;
  56         return &merged;
  57 }
  58
  59 static void match_link_modify(struct sm_state *sm, struct expression *mod_expr)
  60 {
  61         struct expression *expr;
  62         struct sm_state *tmp;
  63
  64         expr = sm->state->data;
  65         if (expr) {
  66                 set_state_expr(size_id, expr, &undefined);
  67                 set_state(link_id, sm->name, sm->sym, &undefined);
  68                 return;
  69         }
  70
  71         FOR_EACH_PTR(sm->possible, tmp) {
  72                 expr = tmp->state->data;
  73                 if (expr)
  74                         set_state_expr(size_id, expr, &undefined);
  75         } END_FOR_EACH_PTR(tmp);
  76         set_state(link_id, sm->name, sm->sym, &undefined);
  77 }
  78
  79 static const char *limit_map[] = {
  80         "byte_count",
  81         "elem_count",
  82         "elem_last",
  83         "used_count",
  84         "used_last",
  85 };
  86
  87 int state_to_limit(struct smatch_state *state)
  88 {
  89         int i;
  90
  91         if (!state || !state->data)
  92                 return -1;
  93
  94         for (i = 0; i < ARRAY_SIZE(limit_map); i++) {
  95                 if (strncmp(state->name, limit_map[i], strlen(limit_map[i])) == 0)
  96                         return i + BYTE_COUNT;
  97         }
  98
  99         return -1;
 100 }
 101
 102 const char *limit_type_str(unsigned int limit_type)
 103 {
 104         if (limit_type - BYTE_COUNT >= ARRAY_SIZE(limit_map)) {
 105                 sm_msg("internal: wrong size type %u", limit_type);
 106                 return "unknown";
 107         }
 108
 109         return limit_map[limit_type - BYTE_COUNT];
 110 }
 111
 112 static struct smatch_state *alloc_compare_size(int limit_type, struct expression *expr)
 113 {
 114         struct smatch_state *state;
 115         char *name;
 116         char buf[256];
 117
 118         state = __alloc_smatch_state(0);
 119         expr = strip_expr(expr);
 120         name = expr_to_str(expr);
 121         snprintf(buf, sizeof(buf), "%s %s", limit_type_str(limit_type), name);
 122         state->name = alloc_sname(buf);
 123         free_string(name);
 124         state->data = expr;
 125         return state;
 126 }
 127
 128 static int bytes_per_element(struct expression *expr)
 129 {
 130         struct symbol *type;
 131
 132         type = get_type(expr);
 133         if (!type)
 134                 return 0;
 135
 136         if (type->type != SYM_PTR && type->type != SYM_ARRAY)
 137                 return 0;
 138
 139         type = get_base_type(type);
 140         return type_bytes(type);
 141 }
 142
 143 static void db_save_type_links(struct expression *array, int type_limit, struct expression *size)
 144 {
 145         const char *array_name;
 146
 147         array_name = get_data_info_name(array);
 148         if (!array_name)
 149                 array_name = "";
 150         sql_insert_data_info(size, type_limit, array_name);
 151 }
 152
 153 static void match_alloc_helper(struct expression *pointer, struct expression *size)
 154 {
 155         struct smatch_state *state;
 156         struct expression *tmp;
 157         struct sm_state *sm;
 158         int limit_type = ELEM_COUNT;
 159         sval_t sval;
 160
 161         pointer = strip_expr(pointer);
 162         size = strip_expr(size);
 163         if (!size || !pointer)
 164                 return;
 165
 166         tmp = get_assigned_expr_recurse(size);
 167         if (tmp && tmp->op == EXPR_BINOP)
 168                 size = strip_expr(tmp);
 169
 170         if (size->type == EXPR_BINOP && size->op == '*') {
 171                 struct expression *mult_left, *mult_right;
 172
 173                 mult_left = strip_expr(size->left);
 174                 mult_right = strip_expr(size->right);
 175
 176                 if (get_implied_value(mult_left, &sval) &&
 177                     sval.value == bytes_per_element(pointer))
 178                         size = mult_right;
 179                 else if (get_implied_value(mult_right, &sval) &&
 180                     sval.value == bytes_per_element(pointer))
 181                         size = mult_left;
 182                 else
 183                         return;
 184         }
 185
 186         /* Only save links to variables, not fixed sizes */
 187         if (get_value(size, &sval))
 188                 return;
 189
 190         if (size->type == EXPR_BINOP && size->op == '+' &&
 191             get_value(size->right, &sval) && sval.value == 1) {
 192                 size = size->left;
 193                 limit_type = ELEM_LAST;
 194         }
 195
 196         db_save_type_links(pointer, limit_type, size);
 197         state = alloc_compare_size(limit_type, size);
 198         sm = set_state_expr(size_id, pointer, state);
 199         if (!sm)
 200                 return;
 201         set_state_expr(link_id, size, alloc_state_expr(pointer));
 202 }
 203
 204 static void match_alloc(const char *fn, struct expression *expr, void *_size_arg)
 205 {
 206         int size_arg = PTR_INT(_size_arg);
 207         struct expression *pointer, *call, *arg;
 208
 209         pointer = strip_expr(expr->left);
 210         call = strip_expr(expr->right);
 211         arg = get_argument_from_call_expr(call->args, size_arg);
 212         match_alloc_helper(pointer, arg);
 213 }
 214
 215 static void match_calloc(const char *fn, struct expression *expr, void *_start_arg)
 216 {
 217         struct smatch_state *state;
 218         int start_arg = PTR_INT(_start_arg);
 219         struct expression *pointer, *call, *arg;
 220         struct sm_state *tmp;
 221         int limit_type = ELEM_COUNT;
 222         sval_t sval;
 223
 224         pointer = strip_expr(expr->left);
 225         call = strip_expr(expr->right);
 226         arg = get_argument_from_call_expr(call->args, start_arg);
 227         if (get_implied_value(arg, &sval) &&
 228             sval.value == bytes_per_element(pointer))
 229                 arg = get_argument_from_call_expr(call->args, start_arg + 1);
 230
 231         if (arg->type == EXPR_BINOP && arg->op == '+' &&
 232             get_value(arg->right, &sval) && sval.value == 1) {
 233                 arg = arg->left;
 234                 limit_type = ELEM_LAST;
 235         }
 236
 237         state = alloc_compare_size(limit_type, arg);
 238         db_save_type_links(pointer, limit_type, arg);
 239         tmp = set_state_expr(size_id, pointer, state);
 240         if (!tmp)
 241                 return;
 242         set_state_expr(link_id, arg, alloc_state_expr(pointer));
 243 }
 244
 245 static struct expression *get_size_variable_from_binop(struct expression *expr, int *limit_type)
 246 {
 247         struct smatch_state *state;
 248         struct expression *ret;
 249         struct symbol *type;
 250         sval_t orig_fixed;
 251         int offset_bytes;
 252         sval_t offset;
 253
 254         if (!get_value(expr->right, &offset))
 255                 return NULL;
 256         state = get_state_expr(size_id, expr->left);
 257         if (!state || !state->data)
 258                 return NULL;
 259
 260         type = get_type(expr->left);
 261         if (!type_is_ptr(type))
 262                 return NULL;
 263         type = get_real_base_type(type);
 264         if (!type_bytes(type))
 265                 return NULL;
 266         offset_bytes = offset.value * type_bytes(type);
 267
 268         ret = state->data;
 269         if (ret->type != EXPR_BINOP || ret->op != '+')
 270                 return NULL;
 271
 272         *limit_type = state_to_limit(state);
 273
 274         if (get_value(ret->left, &orig_fixed) && orig_fixed.value == offset_bytes)
 275                 return ret->right;
 276         if (get_value(ret->right, &orig_fixed) && orig_fixed.value == offset_bytes)
 277                 return ret->left;
 278
 279         return NULL;
 280 }
 281
 282 struct expression *get_size_variable(struct expression *buf, int *limit_type)
 283 {
 284         struct smatch_state *state;
 285         struct expression *ret;
 286
 287         buf = strip_expr(buf);
 288         if (!buf)
 289                 return NULL;
 290         if (buf->type == EXPR_BINOP && buf->op == '+') {
 291                 ret = get_size_variable_from_binop(buf, limit_type);
 292                 if (ret)
 293                         return ret;
 294         }
 295
 296         state = get_state_expr(size_id, buf);
 297         if (!state)
 298                 return NULL;
 299         *limit_type = state_to_limit(state);
 300         return state->data;
 301 }
 302
 303 struct expression *get_array_variable(struct expression *size)
 304 {
 305         struct smatch_state *state;
 306
 307         state = get_state_expr(link_id, size);
 308         if (state)
 309                 return state->data;
 310         return NULL;
 311 }
 312
 313 static void array_check(struct expression *expr)
 314 {
 315         struct expression *array;
 316         struct expression *size;
 317         struct expression *offset;
 318         char *array_str, *offset_str;
 319         int limit_type;
 320
 321         expr = strip_expr(expr);
 322         if (!is_array(expr))
 323                 return;
 324
 325         array = get_array_base(expr);
 326         size = get_size_variable(array, &limit_type);
 327         if (!size)
 328                 return;
 329         if (limit_type != ELEM_COUNT)
 330                 return;
 331         offset = get_array_offset(expr);
 332         if (!possible_comparison(size, SPECIAL_EQUAL, offset))
 333                 return;
 334         if (getting_address(expr))
 335                 return;
 336
 337         array_str = expr_to_str(array);
 338         offset_str = expr_to_str(offset);
 339         sm_warning("potentially one past the end of array '%s[%s]'", array_str, offset_str);
 340         free_string(array_str);
 341         free_string(offset_str);
 342 }
 343
 344 struct db_info {
 345         char *name;
 346         int ret;
 347 };
 348
 349 static int db_limitter_callback(void *_info, int argc, char **argv, char **azColName)
 350 {
 351         struct db_info *info = _info;
 352
 353         /*
 354          * If possible the limitters are tied to the struct they limit.  If we
 355          * aren't sure which struct they limit then we use them as limitters for
 356          * everything.
 357          */
 358         if (!info->name || argv[0][0] == '\0' || strcmp(info->name, argv[0]) == 0)
 359                 info->ret = 1;
 360         return 0;
 361 }
 362
 363 static char *vsl_to_data_info_name(const char *name, struct var_sym_list *vsl)
 364 {
 365         struct var_sym *vs;
 366         struct symbol *type;
 367         static char buf[80];
 368         const char *p;
 369
 370         if (ptr_list_size((struct ptr_list *)vsl) != 1)
 371                 return NULL;
 372         vs = first_ptr_list((struct ptr_list *)vsl);
 373
 374         type = get_real_base_type(vs->sym);
 375         if (!type || type->type != SYM_PTR)
 376                 goto top_level_name;
 377         type = get_real_base_type(type);
 378         if (!type || type->type != SYM_STRUCT)
 379                 goto top_level_name;
 380         if (!type->ident)
 381                 goto top_level_name;
 382
 383         p = name;
 384         while ((name = strstr(p, "->")))
 385                 p = name + 2;
 386
 387         snprintf(buf, sizeof(buf),"(struct %s)->%s", type->ident->name, p);
 388         return alloc_sname(buf);
 389
 390 top_level_name:
 391         if (!(vs->sym->ctype.modifiers & MOD_TOPLEVEL))
 392                 return NULL;
 393         if (vs->sym->ctype.modifiers & MOD_STATIC)
 394                 snprintf(buf, sizeof(buf),"static %s", name);
 395         else
 396                 snprintf(buf, sizeof(buf),"global %s", name);
 397         return alloc_sname(buf);
 398 }
 399
 400 int db_var_is_array_limit(struct expression *array, const char *name, struct var_sym_list *vsl)
 401 {
 402         char *size_name;
 403         char *array_name = get_data_info_name(array);
 404         struct db_info db_info = {.name = array_name,};
 405
 406         size_name = vsl_to_data_info_name(name, vsl);
 407         if (!size_name)
 408                 return 0;
 409
 410         run_sql(db_limitter_callback, &db_info,
 411                 "select value from data_info where type = %d and data = '%s';",
 412                 ARRAY_LEN, size_name);
 413
 414         return db_info.ret;
 415 }
 416
 417 int buf_comparison_index_ok(struct expression *expr)
 418 {
 419         struct expression *array;
 420         struct expression *size;
 421         struct expression *offset;
 422         int limit_type;
 423         int comparison;
 424
 425         array = get_array_base(expr);
 426         size = get_size_variable(array, &limit_type);
 427         if (!size)
 428                 return 0;
 429         offset = get_array_offset(expr);
 430         comparison = get_comparison(offset, size);
 431         if (!comparison)
 432                 return 0;
 433
 434         if ((limit_type == ELEM_COUNT || limit_type == ELEM_LAST) &&
 435             (comparison == '<' || comparison == SPECIAL_UNSIGNED_LT))
 436                 return 1;
 437         if (limit_type == ELEM_LAST &&
 438             (comparison == SPECIAL_LTE ||
 439              comparison == SPECIAL_UNSIGNED_LTE ||
 440              comparison == SPECIAL_EQUAL))
 441                 return 1;
 442
 443         return 0;
 444 }
 445
 446 static int known_access_ok_numbers(struct expression *expr)
 447 {
 448         struct expression *array;
 449         struct expression *offset;
 450         sval_t max;
 451         int size;
 452
 453         array = get_array_base(expr);
 454         offset = get_array_offset(expr);
 455
 456         size = get_array_size(array);
 457         if (size <= 0)
 458                 return 0;
 459
 460         get_absolute_max(offset, &max);
 461         if (max.uvalue < size)
 462                 return 1;
 463         return 0;
 464 }
 465
 466 static void array_check_data_info(struct expression *expr)
 467 {
 468         struct expression *array;
 469         struct expression *offset;
 470         struct state_list *slist;
 471         struct sm_state *sm;
 472         struct compare_data *comp;
 473         char *offset_name;
 474         const char *equal_name = NULL;
 475
 476         expr = strip_expr(expr);
 477         if (!is_array(expr))
 478                 return;
 479
 480         if (known_access_ok_numbers(expr))
 481                 return;
 482         if (buf_comparison_index_ok(expr))
 483                 return;
 484
 485         array = get_array_base(expr);
 486         offset = get_array_offset(expr);
 487         offset_name = expr_to_var(offset);
 488         if (!offset_name)
 489                 return;
 490         slist = get_all_possible_equal_comparisons(offset);
 491         if (!slist)
 492                 goto free;
 493
 494         FOR_EACH_PTR(slist, sm) {
 495                 comp = sm->state->data;
 496                 if (strcmp(comp->left_var, offset_name) == 0) {
 497                         if (db_var_is_array_limit(array, comp->right_var, comp->right_vsl)) {
 498                                 equal_name = comp->right_var;
 499                                 break;
 500                         }
 501                 } else if (strcmp(comp->right_var, offset_name) == 0) {
 502                         if (db_var_is_array_limit(array, comp->left_var, comp->left_vsl)) {
 503                                 equal_name = comp->left_var;
 504                                 break;
 505                         }
 506                 }
 507         } END_FOR_EACH_PTR(sm);
 508
 509         if (equal_name) {
 510                 char *array_name = expr_to_str(array);
 511
 512                 sm_warning("potential off by one '%s[]' limit '%s'", array_name, equal_name);
 513                 free_string(array_name);
 514         }
 515
 516 free:
 517         free_slist(&slist);
 518         free_string(offset_name);
 519 }
 520
 521 static void add_allocation_function(const char *func, void *call_back, int param)
 522 {
 523         add_function_assign_hook(func, call_back, INT_PTR(param));
 524 }
 525
 526 static int is_sizeof(struct expression *expr)
 527 {
 528         const char *name;
 529
 530         if (expr->type == EXPR_SIZEOF)
 531                 return 1;
 532         name = pos_ident(expr->pos);
 533         if (name && strcmp(name, "sizeof") == 0)
 534                 return 1;
 535         return 0;
 536 }
 537
 538 static int match_size_binop(struct expression *size, struct expression *expr, int *limit_type)
 539 {
 540         int orig_type = *limit_type;
 541         struct expression *left;
 542         sval_t sval;
 543
 544         left = expr->left;
 545         if (!expr_equiv(size, left))
 546                 return 0;
 547
 548         if (expr->op == '-' &&
 549             get_value(expr->right, &sval) &&
 550             sval.value == 1 &&
 551             orig_type == ELEM_COUNT) {
 552                 *limit_type = ELEM_LAST;
 553                 return 1;
 554         }
 555
 556         if (expr->op == '+' &&
 557             get_value(expr->right, &sval) &&
 558             sval.value == 1 &&
 559             orig_type == ELEM_LAST) {
 560                 *limit_type = ELEM_COUNT;
 561                 return 1;
 562         }
 563
 564         if (expr->op == '*' &&
 565             is_sizeof(expr->right) &&
 566             orig_type == ELEM_COUNT) {
 567                 *limit_type = BYTE_COUNT;
 568                 return 1;
 569         }
 570
 571         if (expr->op == '/' &&
 572             is_sizeof(expr->right) &&
 573             orig_type == BYTE_COUNT) {
 574                 *limit_type = ELEM_COUNT;
 575                 return 1;
 576         }
 577
 578         return 0;
 579 }
 580
 581 static char *buf_size_param_comparison(struct expression *array, struct expression_list *args, int *limit_type)
 582 {
 583         struct expression *tmp, *arg;
 584         struct expression *size;
 585         static char buf[32];
 586         int i;
 587
 588         size = get_size_variable(array, limit_type);
 589         if (!size)
 590                 return NULL;
 591
 592         if (*limit_type == USED_LAST)
 593                 *limit_type = ELEM_LAST;
 594         if (*limit_type == USED_COUNT)
 595                 *limit_type = ELEM_COUNT;
 596
 597         i = -1;
 598         FOR_EACH_PTR(args, tmp) {
 599                 i++;
 600                 arg = tmp;
 601                 if (arg == array)
 602                         continue;
 603                 if (expr_equiv(arg, size) ||
 604                     (arg->type == EXPR_BINOP &&
 605                      match_size_binop(size, arg, limit_type))) {
 606                         snprintf(buf, sizeof(buf), "==$%d", i);
 607                         return buf;
 608                 }
 609         } END_FOR_EACH_PTR(tmp);
 610
 611         return NULL;
 612 }
 613
 614 static void match_call(struct expression *call)
 615 {
 616         struct expression *arg;
 617         char *compare;
 618         int param;
 619         char buf[5];
 620         int limit_type;
 621
 622         param = -1;
 623         FOR_EACH_PTR(call->args, arg) {
 624                 param++;
 625                 if (!is_pointer(arg))
 626                         continue;
 627                 compare = buf_size_param_comparison(arg, call->args, &limit_type);
 628                 if (!compare)
 629                         continue;
 630                 snprintf(buf, sizeof(buf), "%d", limit_type);
 631                 sql_insert_caller_info(call, limit_type, param, compare, buf);
 632         } END_FOR_EACH_PTR(arg);
 633 }
 634
 635 static int get_param(int param, char **name, struct symbol **sym)
 636 {
 637         struct symbol *arg;
 638         int i;
 639
 640         i = 0;
 641         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
 642                 /*
 643                  * this is a temporary hack to work around a bug (I think in sparse?)
 644                  * 2.6.37-rc1:fs/reiserfs/journal.o
 645                  * If there is a function definition without parameter name found
 646                  * after a function implementation then it causes a crash.
 647                  * int foo() {}
 648                  * int bar(char *);
 649                  */
 650                 if (arg->ident->name < (char *)100)
 651                         continue;
 652                 if (i == param) {
 653                         *name = arg->ident->name;
 654                         *sym = arg;
 655                         return TRUE;
 656                 }
 657                 i++;
 658         } END_FOR_EACH_PTR(arg);
 659
 660         return FALSE;
 661 }
 662
 663 static void set_param_compare(const char *array_name, struct symbol *array_sym, char *key, char *value)
 664 {
 665         struct smatch_state *state;
 666         struct expression *array_expr;
 667         struct expression *size_expr;
 668         struct symbol *size_sym;
 669         char *size_name;
 670         long param;
 671         struct sm_state *tmp;
 672         int limit_type;
 673
 674         if (strncmp(key, "==$", 3) != 0)
 675                 return;
 676         param = strtol(key + 3, NULL, 10);
 677         if (!get_param(param, &size_name, &size_sym))
 678                 return;
 679         array_expr = symbol_expression(array_sym);
 680         size_expr = symbol_expression(size_sym);
 681         limit_type = strtol(value, NULL, 10);
 682
 683         state = alloc_compare_size(limit_type, size_expr);
 684         tmp = set_state_expr(size_id, array_expr, state);
 685         if (!tmp)
 686                 return;
 687         set_state_expr(link_id, size_expr, alloc_state_expr(array_expr));
 688 }
 689
 690 static void set_implied(struct expression *call, struct expression *array_expr, char *key, char *value)
 691 {
 692         struct expression *size_expr;
 693         struct symbol *size_sym;
 694         char *size_name;
 695         long param;
 696         struct sm_state *tmp;
 697         int limit_type;
 698
 699         if (strncmp(key, "==$", 3) != 0)
 700                 return;
 701         param = strtol(key + 3, NULL, 10);
 702         if (!get_param(param, &size_name, &size_sym))
 703                 return;
 704         size_expr = symbol_expression(size_sym);
 705
 706         limit_type = strtol(value, NULL, 10);
 707         tmp = set_state_expr(size_id, array_expr, alloc_compare_size(limit_type, size_expr));
 708         if (!tmp)
 709                 return;
 710         set_state_expr(link_id, size_expr, alloc_state_expr(array_expr));
 711 }
 712
 713 static void munge_start_states(struct statement *stmt)
 714 {
 715         struct state_list *slist = NULL;
 716         struct sm_state *sm;
 717         struct sm_state *poss;
 718
 719         FOR_EACH_MY_SM(size_id, __get_cur_stree(), sm) {
 720                 if (sm->state != &merged)
 721                         continue;
 722                 /*
 723                  * screw it.  let's just assume that if one caller passes the
 724                  * size then they all do.
 725                  */
 726                 FOR_EACH_PTR(sm->possible, poss) {
 727                         if (poss->state != &merged &&
 728                             poss->state != &undefined) {
 729                                 add_ptr_list(&slist, poss);
 730                                 break;
 731                         }
 732                 } END_FOR_EACH_PTR(poss);
 733         } END_FOR_EACH_SM(sm);
 734
 735         FOR_EACH_PTR(slist, sm) {
 736                 set_state(size_id, sm->name, sm->sym, sm->state);
 737         } END_FOR_EACH_PTR(sm);
 738
 739         free_slist(&slist);
 740 }
 741
 742 static void set_used(struct expression *expr)
 743 {
 744         struct expression *parent;
 745         struct expression *array;
 746         struct expression *offset;
 747         struct sm_state *tmp;
 748         int limit_type;
 749
 750         if (expr->op != SPECIAL_INCREMENT)
 751                 return;
 752
 753         limit_type = USED_LAST;
 754         if (expr->type == EXPR_POSTOP)
 755                 limit_type = USED_COUNT;
 756
 757         parent = expr_get_parent_expr(expr);
 758         if (!parent || parent->type != EXPR_BINOP)
 759                 return;
 760         parent = expr_get_parent_expr(parent);
 761         if (!parent || !is_array(parent))
 762                 return;
 763
 764         array = get_array_base(parent);
 765         offset = get_array_offset(parent);
 766         if (offset != expr)
 767                 return;
 768
 769         tmp = set_state_expr(size_id, array, alloc_compare_size(limit_type, offset->unop));
 770         if (!tmp)
 771                 return;
 772         set_state_expr(link_id, offset->unop, alloc_state_expr(array));
 773 }
 774
 775 static int match_assign_array(struct expression *expr)
 776 {
 777         // FIXME: implement
 778         return 0;
 779 }
 780
 781 static int match_assign_size(struct expression *expr)
 782 {
 783         struct expression *right, *size, *array;
 784         struct smatch_state *state;
 785         struct sm_state *tmp;
 786         int limit_type;
 787
 788         right = expr->right;
 789         size = right;
 790         if (size->type == EXPR_BINOP)
 791                 size = size->left;
 792
 793         array = get_array_variable(size);
 794         if (!array)
 795                 return 0;
 796         state = get_state_expr(size_id, array);
 797         if (!state || !state->data)
 798                 return 0;
 799
 800         limit_type = state_to_limit(state);
 801         if (limit_type < 0)
 802                 return 0;
 803
 804         if (right->type == EXPR_BINOP && !match_size_binop(size, right, &limit_type))
 805                 return 0;
 806
 807         tmp = set_state_expr(size_id, array, alloc_compare_size(limit_type, expr->left));
 808         if (!tmp)
 809                 return 0;
 810         set_state_expr(link_id, expr->left, alloc_state_expr(array));
 811         return 1;
 812 }
 813
 814 static void match_assign(struct expression *expr)
 815 {
 816         if (expr->op != '=')
 817                 return;
 818
 819         if (match_assign_array(expr))
 820                 return;
 821         match_assign_size(expr);
 822 }
 823
 824 static void match_copy(const char *fn, struct expression *expr, void *unused)
 825 {
 826         struct expression *src, *size;
 827         int src_param, size_param;
 828
 829         src = get_argument_from_call_expr(expr->args, 1);
 830         size = get_argument_from_call_expr(expr->args, 2);
 831         src = strip_expr(src);
 832         size = strip_expr(size);
 833         if (!src || !size)
 834                 return;
 835         if (src->type != EXPR_SYMBOL || size->type != EXPR_SYMBOL)
 836                 return;
 837
 838         src_param = get_param_num_from_sym(src->symbol);
 839         size_param = get_param_num_from_sym(size->symbol);
 840         if (src_param < 0 || size_param < 0)
 841                 return;
 842
 843         sql_insert_cache(call_implies, "'%s', '%s', 0, %d, %d, %d, '==$%d', '%d'",
 844                          get_base_file(), get_function(), fn_static(),
 845                          BYTE_COUNT, src_param, size_param, BYTE_COUNT);
 846 }
 847
 848 void register_buf_comparison(int id)
 849 {
 850         int i;
 851
 852         size_id = id;
 853
 854         set_dynamic_states(size_id);
 855
 856         add_unmatched_state_hook(size_id, &unmatched_state);
 857
 858         add_allocation_function("malloc", &match_alloc, 0);
 859         add_allocation_function("memdup", &match_alloc, 1);
 860         add_allocation_function("realloc", &match_alloc, 1);
 861         if (option_project == PROJ_KERNEL) {
 862                 add_allocation_function("kmalloc", &match_alloc, 0);
 863                 add_allocation_function("kzalloc", &match_alloc, 0);
 864                 add_allocation_function("vmalloc", &match_alloc, 0);
 865                 add_allocation_function("__vmalloc", &match_alloc, 0);
 866                 add_allocation_function("sock_kmalloc", &match_alloc, 1);
 867                 add_allocation_function("kmemdup", &match_alloc, 1);
 868                 add_allocation_function("memdup_user", &match_alloc, 1);
 869                 add_allocation_function("dma_alloc_attrs", &match_alloc, 1);
 870                 add_allocation_function("dma_alloc_coherent", &match_alloc, 1);
 871                 add_allocation_function("devm_kmalloc", &match_alloc, 1);
 872                 add_allocation_function("devm_kzalloc", &match_alloc, 1);
 873                 add_allocation_function("kcalloc", &match_calloc, 0);
 874                 add_allocation_function("devm_kcalloc", &match_calloc, 1);
 875                 add_allocation_function("kmalloc_array", &match_calloc, 0);
 876                 add_allocation_function("krealloc", &match_alloc, 1);
 877
 878                 add_function_hook("copy_from_user", &match_copy, NULL);
 879                 add_function_hook("__copy_from_user", &match_copy, NULL);
 880         }
 881
 882         add_hook(&array_check, OP_HOOK);
 883         add_hook(&array_check_data_info, OP_HOOK);
 884         add_hook(&set_used, OP_HOOK);
 885
 886         add_hook(&match_call, FUNCTION_CALL_HOOK);
 887         add_hook(&munge_start_states, AFTER_DEF_HOOK);
 888
 889         add_hook(&match_assign, ASSIGNMENT_HOOK);
 890
 891         for (i = BYTE_COUNT; i <= USED_COUNT; i++) {
 892                 select_call_implies_hook(i, &set_implied);
 893                 select_caller_info_hook(set_param_compare, i);
 894                 select_return_implies_hook(i, &set_implied);
 895         }
 896 }
 897
 898 void register_buf_comparison_links(int id)
 899 {
 900         link_id = id;
 901         set_dynamic_states(link_id);
 902         add_merge_hook(link_id, &merge_links);
 903         add_modification_hook(link_id, &match_link_modify);
 904 }