1 /*
2 * Copyright (C) 2013 Oracle.
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 #include "smatch_slist.h"
21
22 static int my_id;
23
24 static int is_comparison_call(struct expression *expr)
25 {
26 expr = expr_get_parent_expr(expr);
27 if (!expr || expr->type != EXPR_COMPARE)
28 return 0;
29 if (expr->op != SPECIAL_EQUAL && expr->op != SPECIAL_NOTEQUAL)
30 return 0;
31 return 1;
32 }
33
34 static int next_line_is_if(struct expression *expr)
35 {
36 struct expression *next;
37
38 if (!__next_stmt || __next_stmt->type != STMT_IF)
39 return 0;
40
41 next = strip_expr(__next_stmt->if_conditional);
42 while (next->type == EXPR_PREOP && next->op == '!')
43 next = strip_expr(next->unop);
44 if (expr_equiv(expr, next))
45 return 1;
46 return 0;
47 }
48
49 static int next_line_checks_IS_ERR(struct expression *call, struct expression *arg)
50 {
51 struct expression *next;
52 struct expression *tmp;
53
54 tmp = expr_get_parent_expr(call);
55 if (tmp && tmp->type == EXPR_ASSIGNMENT) {
56 if (next_line_checks_IS_ERR(NULL, tmp->left))
57 return 1;
58 }
59
60 if (!__next_stmt || __next_stmt->type != STMT_IF)
61 return 0;
62
63 next = strip_expr(__next_stmt->if_conditional);
64 while (next->type == EXPR_PREOP && next->op == '!')
65 next = strip_expr(next->unop);
66 if (!next || next->type != EXPR_CALL)
67 return 0;
68 if (next->fn->type != EXPR_SYMBOL || !next->fn->symbol ||
69 !next->fn->symbol->ident ||
70 (strcmp(next->fn->symbol->ident->name, "IS_ERR") != 0 &&
71 strcmp(next->fn->symbol->ident->name, "IS_ERR_OR_NULL") != 0))
72 return 0;
73 next = get_argument_from_call_expr(next->args, 0);
74 return expr_equiv(next, arg);
75 }
76
77 static int is_non_zero_int(struct range_list *rl)
78 {
79 struct data_range *tmp;
80 int cnt = -1;
81
82 FOR_EACH_PTR(rl, tmp) {
83 cnt++;
84
85 if (cnt == 0) {
86 if (tmp->min.value == INT_MIN &&
87 tmp->max.value == -1)
88 continue;
89 } else if (cnt == 1) {
90 if (tmp->min.value == 1 &&
91 tmp->max.value == INT_MAX)
92 return 1;
93 }
94 return 0;
95 } END_FOR_EACH_PTR(tmp);
96 return 0;
97 }
98
99 static int is_valid_ptr(sval_t sval)
100 {
101 if (sval.value == INT_MIN || sval.value == INT_MAX)
102 return 0;
103
104 if (sval_cmp(valid_ptr_min_sval, sval) <= 0 &&
105 sval_cmp(valid_ptr_max_sval, sval) >= 0) {
106 return 1;
107 }
108 return 0;
109 }
110
111 static int has_distinct_zero(struct range_list *rl)
112 {
113 struct data_range *tmp;
114
115 FOR_EACH_PTR(rl, tmp) {
116 if (tmp->min.value == 0 || tmp->max.value == 0)
117 return 1;
118 } END_FOR_EACH_PTR(tmp);
119 return 0;
120 }
121
122 static void match_err_ptr(const char *fn, struct expression *expr, void *data)
123 {
124 struct expression *arg_expr;
125 struct sm_state *sm, *tmp;
126
127 if (is_impossible_path())
128 return;
129
130 arg_expr = get_argument_from_call_expr(expr->args, 0);
131 sm = get_sm_state_expr(SMATCH_EXTRA, arg_expr);
132 if (!sm)
133 return;
134
135 if (is_comparison_call(expr))
136 return;
137
138 if (next_line_checks_IS_ERR(expr, arg_expr))
139 return;
140 if (strcmp(fn, "ERR_PTR") == 0 &&
141 next_line_is_if(arg_expr))
142 return;
143
144 FOR_EACH_PTR(sm->possible, tmp) {
145 if (!estate_rl(tmp->state))
146 continue;
147 if (is_non_zero_int(estate_rl(tmp->state)))
148 continue;
149 if (has_distinct_zero(estate_rl(tmp->state))) {
150 sm_warning("passing zero to '%s'", fn);
151 return;
152 }
153 if (strcmp(fn, "PTR_ERR") != 0)
154 continue;
155 if (is_valid_ptr(estate_min(tmp->state)) &&
156 is_valid_ptr(estate_max(tmp->state))) {
157 sm_warning("passing a valid pointer to '%s'", fn);
158 return;
159 }
160 } END_FOR_EACH_PTR(tmp);
161 }
162
163 void check_zero_to_err_ptr(int id)
164 {
165 if (option_project != PROJ_KERNEL)
166 return;
167
168 my_id = id;
169 add_function_hook("ERR_PTR", &match_err_ptr, NULL);
170 add_function_hook("ERR_CAST", &match_err_ptr, NULL);
171 add_function_hook("PTR_ERR", &match_err_ptr, NULL);
172 }