states, stree: introduce stree versions of __get_cur_slist() and friends
[smatch.git] / check_deref.c
blob8acbd36838bdfbee65fdaa9fb4e3e5658c626335
1 /*
2 * Copyright (C) 2010 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
19 * There was a previous null dereference test but it was too confusing and
20 * difficult to debug. This test is much simpler in its goals and scope.
22 * This test only complains about:
23 * 1) dereferencing uninitialized variables
24 * 2) dereferencing variables which were assigned as null.
25 * 3) dereferencing variables which were assigned a function the returns
26 * null.
28 * If we dereference something then we complain if any of those three
29 * are possible.
33 #include "smatch.h"
34 #include "smatch_slist.h"
35 #include "smatch_extra.h"
37 static int my_id;
39 #define __GFP_NOFAIL 0x800
41 STATE(null);
42 STATE(ok);
43 STATE(uninitialized);
45 static struct smatch_state *alloc_my_state(const char *name)
47 struct smatch_state *state;
49 state = __alloc_smatch_state(0);
50 state->name = name;
51 return state;
54 static struct smatch_state *unmatched_state(struct sm_state *sm)
56 return &ok;
59 static void is_ok(struct sm_state *sm, struct expression *mod_expr)
61 set_state(my_id, sm->name, sm->sym, &ok);
64 static void check_dereference(struct expression *expr)
66 struct sm_state *sm;
67 struct sm_state *tmp;
69 expr = strip_expr(expr);
70 sm = get_sm_state_expr(my_id, expr);
71 if (!sm)
72 return;
73 if (is_ignored(my_id, sm->name, sm->sym))
74 return;
75 if (implied_not_equal(expr, 0))
76 return;
78 FOR_EACH_PTR(sm->possible, tmp) {
79 if (tmp->state == &merged)
80 continue;
81 if (tmp->state == &ok)
82 continue;
83 add_ignore(my_id, sm->name, sm->sym);
84 if (tmp->state == &null) {
85 if (option_spammy)
86 sm_msg("error: potential NULL dereference '%s'.", tmp->name);
87 return;
89 if (tmp->state == &uninitialized) {
90 if (option_spammy)
91 sm_msg("error: potentially dereferencing uninitialized '%s'.", tmp->name);
92 return;
94 sm_msg("error: potential null dereference '%s'. (%s returns null)",
95 tmp->name, tmp->state->name);
96 return;
97 } END_FOR_EACH_PTR(tmp);
100 static void match_dereferences(struct expression *expr)
102 if (expr->type != EXPR_PREOP)
103 return;
104 check_dereference(expr->unop);
107 static void match_pointer_as_array(struct expression *expr)
109 if (!is_array(expr))
110 return;
111 check_dereference(expr->unop->left);
114 static void set_param_dereferenced(struct expression *arg, char *unused)
116 check_dereference(arg);
119 static void match_declarations(struct symbol *sym)
121 const char *name;
123 if ((get_base_type(sym))->type == SYM_ARRAY)
124 return;
126 if (!sym->ident)
127 return;
128 name = sym->ident->name;
129 if (!sym->initializer) {
130 set_state(my_id, name, sym, &uninitialized);
131 scoped_state(my_id, name, sym);
135 static void match_assign(struct expression *expr)
137 struct statement *stmt;
139 if (!is_zero(expr->right))
140 return;
142 FOR_EACH_PTR_REVERSE(big_statement_stack, stmt) {
143 if (stmt->type == STMT_DECLARATION)
144 return;
145 break;
146 } END_FOR_EACH_PTR_REVERSE(stmt);
148 set_state_expr(my_id, expr->left, &null);
151 static void match_condition(struct expression *expr)
153 if (expr->type == EXPR_ASSIGNMENT) {
154 match_condition(expr->right);
155 match_condition(expr->left);
157 if (!get_state_expr(my_id, expr))
158 return;
159 set_true_false_states_expr(my_id, expr, &ok, NULL);
162 static int called_with_no_fail(struct expression *call, int param)
164 struct expression *arg;
165 sval_t sval;
167 if (param == -1)
168 return 0;
169 call = strip_expr(call);
170 if (call->type != EXPR_CALL)
171 return 0;
172 arg = get_argument_from_call_expr(call->args, param);
173 if (get_value(arg, &sval) && (sval.uvalue & __GFP_NOFAIL))
174 return 1;
175 return 0;
178 static void match_assign_returns_null(const char *fn, struct expression *expr, void *_gfp)
180 struct smatch_state *state;
181 int gfp_param = PTR_INT(_gfp);
183 if (called_with_no_fail(expr->right, gfp_param))
184 return;
185 state = alloc_my_state(fn);
186 set_state_expr(my_id, expr->left, state);
189 static void register_allocation_funcs(void)
191 struct token *token;
192 const char *func;
193 int arg;
195 token = get_tokens_file("kernel.allocation_funcs_gfp");
196 if (!token)
197 return;
198 if (token_type(token) != TOKEN_STREAMBEGIN)
199 return;
200 token = token->next;
201 while (token_type(token) != TOKEN_STREAMEND) {
202 if (token_type(token) != TOKEN_IDENT)
203 return;
204 func = show_ident(token->ident);
205 token = token->next;
206 if (token_type(token) == TOKEN_IDENT)
207 arg = -1;
208 else if (token_type(token) == TOKEN_NUMBER)
209 arg = atoi(token->number);
210 else
211 return;
212 add_function_assign_hook(func, &match_assign_returns_null, INT_PTR(arg));
213 token = token->next;
215 clear_token_alloc();
218 void check_deref(int id)
220 my_id = id;
222 add_unmatched_state_hook(my_id, &unmatched_state);
223 add_modification_hook(my_id, &is_ok);
224 add_hook(&match_dereferences, DEREF_HOOK);
225 add_hook(&match_pointer_as_array, OP_HOOK);
226 select_call_implies_hook(DEREFERENCE, &set_param_dereferenced);
227 add_hook(&match_condition, CONDITION_HOOK);
228 add_hook(&match_declarations, DECLARATION_HOOK);
229 add_hook(&match_assign, ASSIGNMENT_HOOK);
230 if (option_project == PROJ_KERNEL)
231 register_allocation_funcs();