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 static 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
)
61 static struct smatch_state
*unmatched_state(struct sm_state
*sm
)
63 if (sm
->state
== &assumed_nonnull
)
64 return &assumed_nonnull
;
68 static int is_maybe_null_no_arg(const char *name
, struct symbol
*sym
)
70 struct state_list
*slist
;
74 slist
= get_possible_states(name
, my_id
, sym
);
75 FOR_EACH_PTR(slist
, tmp
) {
76 if (tmp
->state
== &ignore
)
78 if (tmp
->state
== &isnull
) {
79 SM_DEBUG("is_maybe_null_no_arg() says %s &isnull\n", name
);
82 if (tmp
->state
== &undefined
) {
83 SM_DEBUG("is_maybe_null_no_arg() says %s &undefined\n", name
);
86 } END_FOR_EACH_PTR(tmp
);
91 static int is_maybe_null(const char *name
, struct symbol
*sym
)
93 struct state_list
*slist
;
97 slist
= get_possible_states(name
, my_id
, sym
);
98 FOR_EACH_PTR(slist
, tmp
) {
99 if (tmp
->state
== &ignore
)
101 if (tmp
->state
== &isnull
) {
102 SM_DEBUG("is_maybe_null() says %s &isnull\n", name
);
105 if (tmp
->state
== &undefined
) {
106 SM_DEBUG("is_maybe_null() says %s &undefined\n", name
);
109 if (tmp
->state
== &arg_null
) {
110 SM_DEBUG("is_maybe_null() says %s &arg_null\n", name
);
113 } END_FOR_EACH_PTR(tmp
);
117 static int is_maybe_null_arg(char *name
, struct symbol
*sym
)
119 struct state_list
*slist
;
120 struct sm_state
*tmp
;
123 slist
= get_possible_states(name
, my_id
, sym
);
124 FOR_EACH_PTR(slist
, tmp
) {
125 if (tmp
->state
!= &argument
&& tmp
->state
!= &arg_null
&&
126 tmp
->state
!= &arg_nonnull
&& tmp
->state
!= &merged
&&
127 tmp
->state
!= &assumed_nonnull
)
129 if (tmp
->state
== &argument
|| tmp
->state
== &arg_null
)
131 } END_FOR_EACH_PTR(tmp
);
133 /* We really only care about arguments if they are null */
137 static struct func_n_param
*alloc_func_n_param(struct symbol
*func
, int param
,
140 struct func_n_param
*tmp
= __alloc_func_n_param(0);
148 static int get_arg_num(struct symbol
*sym
)
153 FOR_EACH_PTR(func_sym
->ctype
.base_type
->arguments
, arg
) {
158 } END_FOR_EACH_PTR(arg
);
162 static void add_do_not_call(struct symbol
*sym
, int line
)
164 struct func_n_param
*tmp
;
165 int num
= get_arg_num(sym
);
167 FOR_EACH_PTR(do_not_call
, tmp
) {
168 if (tmp
->func
== func_sym
&& tmp
->param
== num
)
170 } END_FOR_EACH_PTR(tmp
);
171 tmp
= alloc_func_n_param(func_sym
, num
, line
);
172 add_ptr_list(&do_not_call
, tmp
);
175 static void add_param(struct param_list
**list
, struct symbol
*func
, int param
,
178 struct func_n_param
*tmp
;
180 tmp
= alloc_func_n_param(func
, param
, line
);
181 add_ptr_list(list
, tmp
);
184 static void match_function_def(struct symbol
*sym
)
189 add_param(&funcs
, sym
, 0, 0);
190 FOR_EACH_PTR(sym
->ctype
.base_type
->arguments
, arg
) {
194 set_state(arg
->ident
->name
, my_id
, arg
, &argument
);
195 } END_FOR_EACH_PTR(arg
);
198 static char *get_function_call(struct expression
*expr
)
200 if (expr
->type
!= EXPR_CALL
)
202 if (expr
->fn
->type
== EXPR_SYMBOL
&& expr
->fn
->symbol
)
203 return expr
->fn
->symbol
->ident
->name
;
207 static void match_function_call_after(struct expression
*expr
)
209 struct expression
*tmp
;
212 struct symbol
*func
= NULL
;
215 if (expr
->fn
->type
== EXPR_SYMBOL
)
216 func
= expr
->fn
->symbol
;
219 FOR_EACH_PTR(expr
->args
, tmp
) {
220 tmp
= strip_expr(tmp
);
221 if (tmp
->op
== '&') {
222 name
= get_variable_from_expr(tmp
->unop
, &sym
);
224 set_state(name
, my_id
, sym
, &assumed_nonnull
);
228 name
= get_variable_from_expr(tmp
, &sym
);
229 if (name
&& is_maybe_null_no_arg(name
, sym
))
230 add_param(&calls
, func
, i
, get_lineno());
234 } END_FOR_EACH_PTR(tmp
);
237 static int check_null_returns(const char *name
, struct symbol
*sym
,
238 struct expression
*right
)
243 func_name
= get_function_call(right
);
247 for(i
= 0; i
< sizeof(*return_null
)/sizeof(return_null
[0]); i
++) {
248 if (!strcmp(func_name
, return_null
[i
])) {
249 set_state(name
, my_id
, sym
, &undefined
);
256 static int assign_seen
;
257 static void match_assign(struct expression
*expr
)
259 struct expression
*left
, *right
;
267 left
= strip_expr(expr
->left
);
268 name
= get_variable_from_expr(left
, &sym
);
271 right
= strip_expr(expr
->right
);
272 if (is_zero(right
)) {
273 set_state(name
, my_id
, sym
, &isnull
);
277 if (check_null_returns(name
, sym
, right
)) {
282 /* by default we assume it's assigned something nonnull */
283 set_state(name
, my_id
, sym
, &assumed_nonnull
);
288 * set_new_true_false_paths() is used in the following conditions
289 * if (a) { ... if (a) { ... } }
290 * The problem is that after the second blog a is set to undefined
291 * even though the second condition is meaning less. (The second test
292 * could be a macro for example).
294 * Also, stuff passed to the condition hook is processed behind the scenes
295 * a bit. Instead of a condition like (foo == 0) which is true when foo is
296 * null, we get just (foo) and the true and false states are adjusted later.
297 * Basically the important thing to remember, is that for us, true is always
298 * non null and false is always null.
300 static void set_new_true_false_paths(const char *name
, struct symbol
*sym
)
302 struct smatch_state
*tmp
;
304 tmp
= get_state(name
, my_id
, sym
);
306 SM_DEBUG("set_new_stuff called at for %s on line %d value='%s'\n",
307 name
, get_lineno(), show_state(tmp
));
309 if (tmp
== &argument
) {
310 set_true_false_states(name
, my_id
, sym
, &arg_nonnull
, &arg_null
);
314 if (!tmp
|| is_maybe_null(name
, sym
)) {
315 set_true_false_states(name
, my_id
, sym
, &nonnull
, &isnull
);
321 static void match_condition(struct expression
*expr
)
326 expr
= strip_expr(expr
);
331 name
= get_variable_from_expr(expr
, &sym
);
334 set_new_true_false_paths(name
, sym
);
337 case EXPR_ASSIGNMENT
:
340 * There is a kernel macro that does
341 * for ( ... ; ... || x = NULL ; ) ...
343 if (is_zero(expr
->right
)) {
344 name
= get_variable_from_expr(expr
->left
, &sym
);
347 set_true_false_states(name
, my_id
, sym
, NULL
, &isnull
);
351 /* You have to deal with stuff like if (a = b = c) */
352 match_condition(expr
->right
);
353 match_condition(expr
->left
);
360 static void match_declarations(struct symbol
*sym
)
364 if ((get_base_type(sym
))->type
== SYM_ARRAY
) {
368 name
= sym
->ident
->name
;
370 if (sym
->initializer
) {
371 if (is_zero(sym
->initializer
)) {
372 set_state(name
, my_id
, sym
, &isnull
);
375 if (check_null_returns(name
, sym
, strip_expr(sym
->initializer
)))
377 set_state(name
, my_id
, sym
, &assumed_nonnull
);
379 set_state(name
, my_id
, sym
, &undefined
);
383 static void match_dereferences(struct expression
*expr
)
386 struct symbol
*sym
= NULL
;
388 if (strcmp(show_special(expr
->deref
->op
), "*"))
391 deref
= get_variable_from_expr(expr
->deref
->unop
, &sym
);
395 if (is_maybe_null_arg(deref
, sym
)) {
396 add_do_not_call(sym
, get_lineno());
397 set_state(deref
, my_id
, sym
, &assumed_nonnull
);
398 } else if (is_maybe_null(deref
, sym
)) {
399 smatch_msg("error: dereferencing undefined: '%s'", deref
);
400 set_state(deref
, my_id
, sym
, &ignore
);
405 static void end_file_processing(void)
407 struct func_n_param
*param1
, *param2
;
409 // if a function is not static print it out...
410 FOR_EACH_PTR(do_not_call
, param1
) {
411 if (!(param1
->func
->ctype
.modifiers
& MOD_STATIC
))
412 printf("%s +%d info: unchecked param %s %d\n",
413 get_filename(), param1
->line
,
414 param1
->func
->ident
->name
, param1
->param
);
415 } END_FOR_EACH_PTR(param1
);
417 // if there is an error print it out...
418 FOR_EACH_PTR(calls
, param1
) {
419 FOR_EACH_PTR(do_not_call
, param2
) {
420 if (param1
->func
== param2
->func
&&
421 param1
->param
== param2
->param
)
422 printf("%s +%d error: cross_func deref %s %d\n",
423 get_filename(), param1
->line
,
424 param1
->func
->ident
->name
,
426 } END_FOR_EACH_PTR(param2
);
427 } END_FOR_EACH_PTR(param1
);
429 // if someone calls a non-static function print that..
430 FOR_EACH_PTR(calls
, param1
) {
433 FOR_EACH_PTR(funcs
, param2
) {
434 if (param1
->func
== param2
->func
)
436 } END_FOR_EACH_PTR(param2
);
438 printf("%s +%d info: undefined param %s %d\n",
439 get_filename(), param1
->line
,
440 param1
->func
->ident
->name
, param1
->param
);
441 } END_FOR_EACH_PTR(param1
);
444 void check_null_deref(int id
)
447 add_merge_hook(my_id
, &merge_func
);
448 add_unmatched_state_hook(my_id
, &unmatched_state
);
449 add_hook(&match_function_def
, FUNC_DEF_HOOK
);
450 add_hook(&match_function_call_after
, FUNCTION_CALL_AFTER_HOOK
);
451 add_hook(&match_assign
, ASSIGNMENT_AFTER_HOOK
);
452 add_hook(&match_condition
, CONDITION_HOOK
);
453 add_hook(&match_dereferences
, DEREF_HOOK
);
454 add_hook(&match_declarations
, DECLARATION_HOOK
);
455 add_hook(&end_file_processing
, END_FILE_HOOK
);