check_free_strict: New stricter cross function use after free check
[smatch.git] / check_err_ptr_deref.c
blob07e2a48091c886154797c9a405f01f88b34d9d4d
1 /*
2 * Copyright (C) 2009 Dan Carpenter.
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.
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.
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
18 #include "smatch.h"
19 #include "smatch_slist.h"
20 #include "smatch_extra.h"
22 static int my_id;
24 STATE(err_ptr);
25 STATE(checked);
27 static sval_t err_ptr_min = {
28 .type = &int_ctype,
29 {.value = -4095},
32 static sval_t err_ptr_max = {
33 .type = &int_ctype,
34 {.value = -1},
37 struct range_list *err_ptr_rl;
39 static void ok_to_use(struct sm_state *sm, struct expression *mod_expr)
41 if (sm->state != &checked)
42 set_state(my_id, sm->name, sm->sym, &checked);
45 static void check_is_err_ptr(struct expression *expr)
47 struct sm_state *sm;
48 struct range_list *rl;
50 sm = get_sm_state_expr(my_id, expr);
51 if (!sm)
52 return;
54 if (!slist_has_state(sm->possible, &err_ptr))
55 return;
57 get_absolute_rl(expr, &rl);
58 if (!possibly_true_rl(rl, SPECIAL_EQUAL, err_ptr_rl))
59 return;
61 sm_msg("error: '%s' dereferencing possible ERR_PTR()", sm->name);
62 set_state(my_id, sm->name, sm->sym, &checked);
65 static void match_returns_err_ptr(const char *fn, struct expression *expr,
66 void *info)
68 set_state_expr(my_id, expr->left, &err_ptr);
71 static void set_param_dereferenced(struct expression *call, struct expression *arg, char *key, char *unused)
73 struct sm_state *sm;
74 struct smatch_state *estate;
75 struct symbol *sym;
76 char *name;
78 name = get_variable_from_key(arg, key, &sym);
79 if (!name || !sym)
80 goto free;
82 sm = get_sm_state(my_id, name, sym);
83 if (!sm)
84 goto free;
86 if (!slist_has_state(sm->possible, &err_ptr))
87 goto free;
89 estate = get_state(SMATCH_EXTRA, name, sym);
90 if (!estate || !possibly_true_rl(estate_rl(estate), SPECIAL_EQUAL, err_ptr_rl))
91 goto free;
93 sm_msg("error: '%s' dereferencing possible ERR_PTR()", sm->name);
94 set_state(my_id, sm->name, sm->sym, &checked);
96 free:
97 free_string(name);
100 static void match_checked(const char *fn, struct expression *call_expr,
101 struct expression *assign_expr, void *unused)
103 struct expression *arg;
105 arg = get_argument_from_call_expr(call_expr->args, 0);
106 arg = strip_expr(arg);
107 while (arg->type == EXPR_ASSIGNMENT)
108 arg = strip_expr(arg->left);
109 set_state_expr(my_id, arg, &checked);
112 static void match_err(const char *fn, struct expression *call_expr,
113 struct expression *assign_expr, void *unused)
115 struct expression *arg;
117 arg = get_argument_from_call_expr(call_expr->args, 0);
118 arg = strip_expr(arg);
119 while (arg->type == EXPR_ASSIGNMENT)
120 arg = strip_expr(arg->left);
121 set_state_expr(my_id, arg, &err_ptr);
124 static void match_dereferences(struct expression *expr)
126 if (expr->type != EXPR_PREOP)
127 return;
128 check_is_err_ptr(expr->unop);
131 static void match_kfree(const char *fn, struct expression *expr, void *_arg_nr)
133 int arg_nr = PTR_INT(_arg_nr);
134 struct expression *arg;
136 arg = get_argument_from_call_expr(expr->args, arg_nr);
137 check_is_err_ptr(arg);
140 static void match_condition(struct expression *expr)
142 if (expr->type == EXPR_ASSIGNMENT) {
143 match_condition(expr->right);
144 match_condition(expr->left);
146 if (!get_state_expr(my_id, expr))
147 return;
148 /* If we know the variable is zero that means it's not an ERR_PTR */
149 set_true_false_states_expr(my_id, expr, NULL, &checked);
152 static void register_err_ptr_funcs(void)
154 struct token *token;
155 const char *func;
157 token = get_tokens_file("kernel.returns_err_ptr");
158 if (!token)
159 return;
160 if (token_type(token) != TOKEN_STREAMBEGIN)
161 return;
162 token = token->next;
163 while (token_type(token) != TOKEN_STREAMEND) {
164 if (token_type(token) != TOKEN_IDENT)
165 return;
166 func = show_ident(token->ident);
167 add_function_assign_hook(func, &match_returns_err_ptr, NULL);
168 token = token->next;
170 clear_token_alloc();
173 static void match_err_ptr_positive_const(const char *fn, struct expression *expr, void *unused)
175 struct expression *arg;
176 sval_t sval;
178 arg = get_argument_from_call_expr(expr->args, 0);
180 if (!get_value(arg, &sval))
181 return;
182 if (sval_is_positive(sval) && sval_cmp_val(sval, 0) != 0)
183 sm_msg("error: passing non negative %s to ERR_PTR", sval_to_str(sval));
186 static void match_err_ptr(const char *fn, struct expression *expr, void *unused)
188 struct expression *arg;
189 struct sm_state *sm;
190 struct sm_state *tmp;
191 sval_t tmp_min;
192 sval_t tmp_max;
193 sval_t min = sval_type_max(&llong_ctype);
194 sval_t max = sval_type_min(&llong_ctype);
196 arg = get_argument_from_call_expr(expr->args, 0);
197 sm = get_sm_state_expr(SMATCH_EXTRA, arg);
198 if (!sm)
199 return;
200 FOR_EACH_PTR(sm->possible, tmp) {
201 tmp_min = estate_min(tmp->state);
202 if (!sval_is_a_min(tmp_min) && sval_cmp(tmp_min, min) < 0)
203 min = tmp_min;
204 tmp_max = estate_max(tmp->state);
205 if (!sval_is_a_max(tmp_max) && sval_cmp(tmp_max, max) > 0)
206 max = tmp_max;
207 } END_FOR_EACH_PTR(tmp);
208 if (sval_is_negative(min) && sval_cmp_val(min, -4095) < 0)
209 sm_msg("error: %s too low for ERR_PTR", sval_to_str(min));
210 if (sval_is_positive(max) && sval_cmp_val(max, 0) != 0)
211 sm_msg("error: passing non negative %s to ERR_PTR", sval_to_str(max));
214 void check_err_ptr_deref(int id)
216 if (option_project != PROJ_KERNEL)
217 return;
219 my_id = id;
220 return_implies_state("IS_ERR", 0, 0, &match_checked, NULL);
221 return_implies_state("IS_ERR", 1, 1, &match_err, NULL);
222 return_implies_state("IS_ERR_OR_NULL", 0, 0, &match_checked, NULL);
223 return_implies_state("IS_ERR_OR_NULL", 1, 1, &match_err, NULL);
224 return_implies_state("PTR_RET", 0, 0, &match_checked, NULL);
225 return_implies_state("PTR_RET", -4096, -1, &match_err, NULL);
226 register_err_ptr_funcs();
227 add_hook(&match_dereferences, DEREF_HOOK);
228 add_function_hook("ERR_PTR", &match_err_ptr_positive_const, NULL);
229 add_function_hook("ERR_PTR", &match_err_ptr, NULL);
230 add_hook(&match_condition, CONDITION_HOOK);
231 add_modification_hook(my_id, &ok_to_use);
232 add_function_hook("kfree", &match_kfree, INT_PTR(0));
233 add_function_hook("brelse", &match_kfree, INT_PTR(0));
234 add_function_hook("kmem_cache_free", &match_kfree, INT_PTR(1));
235 add_function_hook("vfree", &match_kfree, INT_PTR(0));
237 err_ptr_rl = clone_rl_permanent(alloc_rl(err_ptr_min, err_ptr_max));
239 select_call_implies_hook(DEREFERENCE, &set_param_dereferenced);