2 * sparse/check_deference.c
4 * Copyright (C) 2006 Dan Carpenter.
6 * Licensed under the Open Software License version 1.1
12 #include "smatch_slist.h"
15 * TODO: The return_null list of functions should be determined automatically
17 const char *return_null
[] = {
26 ALLOCATOR(func_n_param
, "func parameters");
27 DECLARE_PTR_LIST(param_list
, struct func_n_param
);
29 static struct param_list
*funcs
;
30 static struct param_list
*do_not_call
;
31 static struct param_list
*calls
;
38 STATE(assumed_nonnull
);
43 static struct symbol
*func_sym
;
46 * merge_func() is to handle assumed_nonnull.
48 * Assumed_nonnull is a funny state. It's almost the same as
49 * no state. Maybe it would be better to delete it completely...
51 static struct smatch_state
*merge_func(const char *name
, struct symbol
*sym
,
52 struct smatch_state
*s1
,
53 struct smatch_state
*s2
)
55 if (s1
== &ignore
|| s2
== &ignore
)
57 if (s1
== NULL
&& s2
== &assumed_nonnull
)
58 return &assumed_nonnull
;
65 static int is_maybe_null_no_arg(const char *name
, struct symbol
*sym
)
67 struct state_list
*slist
;
71 slist
= get_possible_states(name
, my_id
, sym
);
72 FOR_EACH_PTR(slist
, tmp
) {
73 if (tmp
->state
== &ignore
)
75 if (tmp
->state
== &isnull
) {
76 SM_DEBUG("is_maybe_null_no_arg() says %s &isnull\n", name
);
79 if (tmp
->state
== &undefined
) {
80 SM_DEBUG("is_maybe_null_no_arg() says %s &undefined\n", name
);
83 } END_FOR_EACH_PTR(tmp
);
88 static int is_maybe_null(const char *name
, struct symbol
*sym
)
90 struct state_list
*slist
;
94 slist
= get_possible_states(name
, my_id
, sym
);
95 FOR_EACH_PTR(slist
, tmp
) {
96 if (tmp
->state
== &ignore
)
98 if (tmp
->state
== &isnull
) {
99 SM_DEBUG("is_maybe_null() says %s &isnull\n", name
);
102 if (tmp
->state
== &undefined
) {
103 SM_DEBUG("is_maybe_null() says %s &undefined\n", name
);
106 if (tmp
->state
== &arg_null
) {
107 SM_DEBUG("is_maybe_null() says %s &arg_null\n", name
);
110 } END_FOR_EACH_PTR(tmp
);
114 static int is_maybe_null_arg(char *name
, struct symbol
*sym
)
116 struct state_list
*slist
;
117 struct sm_state
*tmp
;
120 slist
= get_possible_states(name
, my_id
, sym
);
121 FOR_EACH_PTR(slist
, tmp
) {
122 if (tmp
->state
!= &argument
&& tmp
->state
!= &arg_null
&&
123 tmp
->state
!= &arg_nonnull
&& tmp
->state
!= &merged
&&
124 tmp
->state
!= &assumed_nonnull
)
126 if (tmp
->state
== &argument
|| tmp
->state
== &arg_null
)
128 } END_FOR_EACH_PTR(tmp
);
130 /* We really only care about arguments if they are null */
134 static struct func_n_param
*alloc_func_n_param(struct symbol
*func
, int param
,
137 struct func_n_param
*tmp
= __alloc_func_n_param(0);
145 static int get_arg_num(struct symbol
*sym
)
150 FOR_EACH_PTR(func_sym
->ctype
.base_type
->arguments
, arg
) {
155 } END_FOR_EACH_PTR(arg
);
159 static void add_do_not_call(struct symbol
*sym
, int line
)
161 struct func_n_param
*tmp
;
162 int num
= get_arg_num(sym
);
164 FOR_EACH_PTR(do_not_call
, tmp
) {
165 if (tmp
->func
== func_sym
&& tmp
->param
== num
)
167 } END_FOR_EACH_PTR(tmp
);
168 tmp
= alloc_func_n_param(func_sym
, num
, line
);
169 add_ptr_list(&do_not_call
, tmp
);
172 static void add_param(struct param_list
**list
, struct symbol
*func
, int param
,
175 struct func_n_param
*tmp
;
177 tmp
= alloc_func_n_param(func
, param
, line
);
178 add_ptr_list(list
, tmp
);
181 static void match_function_def(struct symbol
*sym
)
186 add_param(&funcs
, sym
, 0, 0);
187 FOR_EACH_PTR(sym
->ctype
.base_type
->arguments
, arg
) {
191 set_state(arg
->ident
->name
, my_id
, arg
, &argument
);
192 } END_FOR_EACH_PTR(arg
);
195 static char *get_function_call(struct expression
*expr
)
197 if (expr
->type
!= EXPR_CALL
)
199 if (expr
->fn
->type
== EXPR_SYMBOL
&& expr
->fn
->symbol
)
200 return expr
->fn
->symbol
->ident
->name
;
204 static void match_function_call_after(struct expression
*expr
)
206 struct expression
*tmp
;
209 struct symbol
*func
= NULL
;
212 if (expr
->fn
->type
== EXPR_SYMBOL
)
213 func
= expr
->fn
->symbol
;
216 FOR_EACH_PTR(expr
->args
, tmp
) {
217 tmp
= strip_expr(tmp
);
218 if (tmp
->op
== '&') {
219 name
= get_variable_from_expr(tmp
->unop
, &sym
);
221 set_state(name
, my_id
, sym
, &assumed_nonnull
);
225 name
= get_variable_from_expr(tmp
, &sym
);
226 if (name
&& is_maybe_null_no_arg(name
, sym
))
227 add_param(&calls
, func
, i
, get_lineno());
231 } END_FOR_EACH_PTR(tmp
);
234 static int check_null_returns(const char *name
, struct symbol
*sym
,
235 struct expression
*right
)
240 func_name
= get_function_call(right
);
244 for(i
= 0; i
< sizeof(*return_null
)/sizeof(return_null
[0]); i
++) {
245 if (!strcmp(func_name
, return_null
[i
])) {
246 set_state(name
, my_id
, sym
, &undefined
);
253 static int assign_seen
;
254 static void match_assign(struct expression
*expr
)
256 struct expression
*left
, *right
;
264 left
= strip_expr(expr
->left
);
265 name
= get_variable_from_expr(left
, &sym
);
268 right
= strip_expr(expr
->right
);
269 if (is_zero(right
)) {
270 set_state(name
, my_id
, sym
, &isnull
);
274 if (check_null_returns(name
, sym
, right
)) {
279 /* by default we assume it's assigned something nonnull */
280 set_state(name
, my_id
, sym
, &assumed_nonnull
);
285 * set_new_true_false_paths() is used in the following conditions
286 * if (a) { ... if (a) { ... } }
287 * The problem is that after the second blog a is set to undefined
288 * even though the second condition is meaning less. (The second test
289 * could be a macro for example).
291 * Also, stuff passed to the condition hook is processed behind the scenes
292 * a bit. Instead of a condition like (foo == 0) which is true when foo is
293 * null, we get just (foo) and the true and false states are adjusted later.
294 * Basically the important thing to remember, is that for us, true is always
295 * non null and false is always null.
297 static void set_new_true_false_paths(const char *name
, struct symbol
*sym
)
299 struct smatch_state
*tmp
;
301 tmp
= get_state(name
, my_id
, sym
);
303 SM_DEBUG("set_new_stuff called at for %s on line %d value='%s'\n",
304 name
, get_lineno(), show_state(tmp
));
306 if (tmp
== &argument
) {
307 set_true_false_states(name
, my_id
, sym
, &arg_nonnull
, &arg_null
);
311 if (!tmp
|| is_maybe_null(name
, sym
)) {
312 set_true_false_states(name
, my_id
, sym
, &nonnull
, &isnull
);
318 static void match_condition(struct expression
*expr
)
323 expr
= strip_expr(expr
);
328 name
= get_variable_from_expr(expr
, &sym
);
331 set_new_true_false_paths(name
, sym
);
334 case EXPR_ASSIGNMENT
:
337 * There is a kernel macro that does
338 * for ( ... ; ... || x = NULL ; ) ...
340 if (is_zero(expr
->right
)) {
341 name
= get_variable_from_expr(expr
->left
, &sym
);
344 set_true_false_states(name
, my_id
, sym
, NULL
, &isnull
);
348 /* You have to deal with stuff like if (a = b = c) */
349 match_condition(expr
->right
);
350 match_condition(expr
->left
);
357 static void match_declarations(struct symbol
*sym
)
361 if ((get_base_type(sym
))->type
== SYM_ARRAY
) {
365 name
= sym
->ident
->name
;
367 if (sym
->initializer
) {
368 if (is_zero(sym
->initializer
)) {
369 set_state(name
, my_id
, sym
, &isnull
);
372 if (check_null_returns(name
, sym
, strip_expr(sym
->initializer
)))
374 set_state(name
, my_id
, sym
, &assumed_nonnull
);
376 set_state(name
, my_id
, sym
, &undefined
);
380 static void match_dereferences(struct expression
*expr
)
383 struct symbol
*sym
= NULL
;
385 if (strcmp(show_special(expr
->deref
->op
), "*"))
388 deref
= get_variable_from_expr(expr
->deref
->unop
, &sym
);
392 if (is_maybe_null_arg(deref
, sym
)) {
393 add_do_not_call(sym
, get_lineno());
394 set_state(deref
, my_id
, sym
, &assumed_nonnull
);
395 } else if (is_maybe_null(deref
, sym
)) {
396 smatch_msg("error: dereferencing undefined: '%s'", deref
);
397 set_state(deref
, my_id
, sym
, &ignore
);
402 static void end_file_processing()
404 struct func_n_param
*param1
, *param2
;
406 // if a function is not static print it out...
407 FOR_EACH_PTR(do_not_call
, param1
) {
408 if (!(param1
->func
->ctype
.modifiers
& MOD_STATIC
))
409 printf("%s +%d info: unchecked param %s %d\n",
410 get_filename(), param1
->line
,
411 param1
->func
->ident
->name
, param1
->param
);
412 } END_FOR_EACH_PTR(param1
);
414 // if there is an error print it out...
415 FOR_EACH_PTR(calls
, param1
) {
416 FOR_EACH_PTR(do_not_call
, param2
) {
417 if (param1
->func
== param2
->func
&&
418 param1
->param
== param2
->param
)
419 printf("%s +%d error: cross_func deref %s %d\n",
420 get_filename(), param1
->line
,
421 param1
->func
->ident
->name
,
423 } END_FOR_EACH_PTR(param2
);
424 } END_FOR_EACH_PTR(param1
);
426 // if someone calls a non-static function print that..
427 FOR_EACH_PTR(calls
, param1
) {
430 FOR_EACH_PTR(funcs
, param2
) {
431 if (param1
->func
== param2
->func
)
433 } END_FOR_EACH_PTR(param2
);
435 printf("%s +%d info: undefined param %s %d\n",
436 get_filename(), param1
->line
,
437 param1
->func
->ident
->name
, param1
->param
);
438 } END_FOR_EACH_PTR(param1
);
441 void check_null_deref(int id
)
444 add_merge_hook(my_id
, &merge_func
);
445 add_hook(&match_function_def
, FUNC_DEF_HOOK
);
446 add_hook(&match_function_call_after
, FUNCTION_CALL_AFTER_HOOK
);
447 add_hook(&match_assign
, ASSIGNMENT_AFTER_HOOK
);
448 add_hook(&match_condition
, CONDITION_HOOK
);
449 add_hook(&match_dereferences
, DEREF_HOOK
);
450 add_hook(&match_declarations
, DECLARATION_HOOK
);
451 add_hook(&end_file_processing
, END_FILE_HOOK
);