1 /*
2 * Copyright (C) 2010 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_slist.h"
20 #include "smatch_extra.h"
21
22 static int my_id;
23
ok_to_use(struct sm_state * sm,struct expression * mod_expr)24 static void ok_to_use(struct sm_state *sm, struct expression *mod_expr)
25 {
26 set_state(my_id, sm->name, sm->sym, &undefined);
27 }
28
match_snprintf(const char * fn,struct expression * expr,void * info)29 static void match_snprintf(const char *fn, struct expression *expr, void *info)
30 {
31 struct expression *call;
32 struct expression *arg;
33 sval_t buflen;
34
35 call = strip_expr(expr->right);
36 arg = get_argument_from_call_expr(call->args, 1);
37 if (!get_fuzzy_max(arg, &buflen))
38 return;
39 set_state_expr(my_id, expr->left, alloc_state_num(buflen.value));
40 }
41
get_old_buflen(struct sm_state * sm)42 static int get_old_buflen(struct sm_state *sm)
43 {
44 struct sm_state *tmp;
45 int ret = 0;
46
47 FOR_EACH_PTR(sm->possible, tmp) {
48 if (PTR_INT(tmp->state->data) > ret)
49 ret = PTR_INT(tmp->state->data);
50 } END_FOR_EACH_PTR(tmp);
51 return ret;
52 }
53
match_call(struct expression * expr)54 static void match_call(struct expression *expr)
55 {
56 struct expression *arg;
57 struct sm_state *sm;
58 int old_buflen;
59 sval_t max;
60
61 FOR_EACH_PTR(expr->args, arg) {
62 sm = get_sm_state_expr(my_id, arg);
63 if (!sm)
64 continue;
65 old_buflen = get_old_buflen(sm);
66 if (!old_buflen)
67 return;
68 if (get_absolute_max(arg, &max) && sval_cmp_val(max, old_buflen) > 0)
69 sm_warning("'%s' returned from snprintf() might be larger than %d",
70 sm->name, old_buflen);
71 } END_FOR_EACH_PTR(arg);
72 }
73
check_snprintf(int id)74 void check_snprintf(int id)
75 {
76 if (option_project != PROJ_KERNEL)
77 return;
78 if (!option_spammy)
79 return;
80
81 my_id = id;
82 set_dynamic_states(my_id);
83 add_hook(&match_call, FUNCTION_CALL_HOOK);
84 add_function_assign_hook("snprintf", &match_snprintf, NULL);
85 add_modification_hook(my_id, &ok_to_use);
86 }
87
88