1 /*
2  * Copyright (C) 2009 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 
21 static int my_id;
22 
23 static int err_ptr = 0;
24 static int returns_null = 0;
25 
match_err_ptr(struct expression * expr)26 static void match_err_ptr(struct expression *expr)
27 {
28 	expr = strip_expr(expr);
29 	if (!expr)
30 		return;
31 	if (expr->type != EXPR_CALL)
32 		return;
33 
34 	if (expr->fn->type != EXPR_SYMBOL || !expr->fn->symbol)
35 		return;
36 	if (!strcmp(expr->fn->symbol->ident->name, "ERR_PTR"))
37 		err_ptr = 1;
38 }
39 
match_return(struct expression * ret_value)40 static void match_return(struct expression *ret_value)
41 {
42 	struct state_list *slist;
43 	struct sm_state *tmp;
44 	sval_t sval;
45 
46 	if (__inline_fn)
47 		return;
48 	match_err_ptr(ret_value);
49 	slist = get_possible_states_expr(check_assigned_expr_id, ret_value);
50 	FOR_EACH_PTR(slist, tmp) {
51 		if (tmp->state == &undefined || tmp->state == &merged)
52 			continue;
53 		match_err_ptr((struct expression *)tmp->state->data);
54 	} END_FOR_EACH_PTR(tmp);
55 
56 	if (get_implied_value(ret_value, &sval)) {
57 		if (sval.value == 0)
58 			returns_null = 1;
59 	}
60 }
61 
match_end_func(struct symbol * sym)62 static void match_end_func(struct symbol *sym)
63 {
64 	if (__inline_fn)
65 		return;
66 	if (err_ptr)
67 		sm_info("returns_err_ptr");
68 	err_ptr = 0;
69 	returns_null = 0;
70 }
71 
check_err_ptr(int id)72 void check_err_ptr(int id)
73 {
74 	if (option_project != PROJ_KERNEL)
75 		return;
76 	if (!option_info)
77 		return;
78 
79 	my_id = id;
80 	add_hook(&match_return, RETURN_HOOK);
81 	add_hook(&match_end_func, END_FUNC_HOOK);
82 }
83