xref: /illumos-gate/usr/src/tools/smatch/src/check_deref_check.c (revision c85f09cc92abd00c84e58ec9f0f5d942906cb713)
1 /*
2  * Copyright (C) 2009 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 #include "smatch.h"
19 #include "smatch_extra.h"
20 
21 static int my_id;
22 
23 STATE(derefed);
24 
underef(struct sm_state * sm,struct expression * mod_expr)25 static void underef(struct sm_state *sm, struct expression *mod_expr)
26 {
27 	set_state(my_id, sm->name, sm->sym, &undefined);
28 }
29 
match_dereference(struct expression * expr)30 static void match_dereference(struct expression *expr)
31 {
32 	if (__in_fake_assign)
33 		return;
34 
35 	if (expr->type != EXPR_PREOP)
36 		return;
37 	expr = strip_expr(expr->unop);
38 	if (!is_pointer(expr))
39 		return;
40 	if (implied_not_equal(expr, 0))
41 		return;
42 
43 	if (is_impossible_path())
44 		return;
45 
46 	set_state_expr(my_id, expr, &derefed);
47 }
48 
set_param_dereferenced(struct expression * call,struct expression * arg,char * key,char * unused)49 static void set_param_dereferenced(struct expression *call, struct expression *arg, char *key, char *unused)
50 {
51 	struct symbol *sym;
52 	char *name;
53 
54 	name = get_variable_from_key(arg, key, &sym);
55 	if (!name || !sym)
56 		goto free;
57 
58 	if (implied_not_equal_name_sym(name, sym, 0))
59 		goto free;
60 	set_state(my_id, name, sym, &derefed);
61 
62 free:
63 	free_string(name);
64 }
65 
match_condition(struct expression * expr)66 static void match_condition(struct expression *expr)
67 {
68 	struct sm_state *sm;
69 	char *name;
70 
71 	if (__in_pre_condition)
72 		return;
73 
74 	name = get_macro_name(expr->pos);
75 	if (name &&
76 	    (strcmp(name, "likely") != 0 && strcmp(name, "unlikely") != 0))
77 		return;
78 
79 	if (!is_pointer(expr))
80 		return;
81 
82 	sm = get_sm_state_expr(my_id, expr);
83 	if (!sm || sm->state != &derefed)
84 		return;
85 
86 	sm_warning("variable dereferenced before check '%s' (see line %d)", sm->name, sm->line);
87 	set_state_expr(my_id, expr, &undefined);
88 }
89 
check_deref_check(int id)90 void check_deref_check(int id)
91 {
92 	my_id = id;
93 	add_hook(&match_dereference, DEREF_HOOK);
94 	add_hook(&match_condition, CONDITION_HOOK);
95 	select_return_implies_hook(DEREFERENCE, &set_param_dereferenced);
96 	add_modification_hook(my_id, &underef);
97 }
98