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 <stdlib.h>
19 #include "parse.h"
20 #include "smatch.h"
21 #include "smatch_slist.h"
22 #include "smatch_extra.h"
23
24 /*
25 * This check has two smatch IDs.
26 * my_used_id - keeps a record of array offsets that have been used.
27 * If the code checks that they are within bounds later on,
28 * we complain about using an array offset before checking
29 * that it is within bounds.
30 */
31 static int my_used_id;
32
delete(struct sm_state * sm,struct expression * mod_expr)33 static void delete(struct sm_state *sm, struct expression *mod_expr)
34 {
35 set_state(my_used_id, sm->name, sm->sym, &undefined);
36 }
37
array_check(struct expression * expr)38 static void array_check(struct expression *expr)
39 {
40 struct expression *array_expr;
41 int array_size;
42 struct expression *offset;
43 struct range_list *rl;
44
45 expr = strip_expr(expr);
46 if (!is_array(expr))
47 return;
48
49 array_expr = get_array_base(expr);
50 array_size = get_array_size(array_expr);
51 if (!array_size || array_size == 1)
52 return;
53
54 offset = get_array_offset(expr);
55 get_absolute_rl(offset, &rl);
56 if (rl_max(rl).uvalue < array_size)
57 return;
58 if (buf_comparison_index_ok(expr))
59 return;
60
61 if (getting_address(expr))
62 return;
63 if (is_capped(offset))
64 return;
65 set_state_expr(my_used_id, offset, alloc_state_num(array_size));
66 }
67
match_condition(struct expression * expr)68 static void match_condition(struct expression *expr)
69 {
70 int left;
71 sval_t sval;
72 struct state_list *slist;
73 struct sm_state *tmp;
74 int boundary;
75
76 if (!expr || expr->type != EXPR_COMPARE)
77 return;
78 if (get_macro_name(expr->pos))
79 return;
80 if (get_implied_value(expr->left, &sval))
81 left = 1;
82 else if (get_implied_value(expr->right, &sval))
83 left = 0;
84 else
85 return;
86
87 if (left)
88 slist = get_possible_states_expr(my_used_id, expr->right);
89 else
90 slist = get_possible_states_expr(my_used_id, expr->left);
91 if (!slist)
92 return;
93 FOR_EACH_PTR(slist, tmp) {
94 if (tmp->state == &merged || tmp->state == &undefined)
95 continue;
96 boundary = PTR_INT(tmp->state->data);
97 boundary -= sval.value;
98 if (boundary < 1 && boundary > -1) {
99 char *name;
100
101 name = expr_to_var(left ? expr->right : expr->left);
102 sm_error("testing array offset '%s' after use.", name);
103 return;
104 }
105 } END_FOR_EACH_PTR(tmp);
106 }
107
check_testing_index_after_use(int id)108 void check_testing_index_after_use(int id)
109 {
110 my_used_id = id;
111 set_dynamic_states(my_used_id);
112 add_hook(&array_check, OP_HOOK);
113 add_hook(&match_condition, CONDITION_HOOK);
114 add_modification_hook(my_used_id, &delete);
115 }
116