1/*
2 * Copyright (C) 2014 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
20static int my_id;
21
22STATE(too_small);
23
24static void match_assign(struct expression *expr)
25{
26	struct symbol *left_type, *right_type;
27	struct expression *size_expr;
28	sval_t min_size;
29	int limit_type;
30	int bytes;
31
32	left_type = get_type(expr->left);
33	if (!left_type || left_type->type != SYM_PTR)
34		return;
35	left_type = get_real_base_type(left_type);
36	if (!left_type || left_type->type != SYM_STRUCT)
37		return;
38
39	right_type = get_type(expr->right);
40	if (!right_type || right_type->type != SYM_PTR)
41		return;
42	right_type = get_real_base_type(right_type);
43	if (!right_type)
44		return;
45	if (right_type != &void_ctype && type_bits(right_type) != 8)
46		return;
47
48	bytes = get_array_size_bytes(expr->right);
49	if (bytes >= type_bytes(left_type))
50		return;
51
52	size_expr = get_size_variable(expr->right, &limit_type);
53	if (!size_expr)
54		return;
55	if (limit_type != ELEM_COUNT)
56		return;
57
58	get_absolute_min(size_expr, &min_size);
59	if (min_size.value >= type_bytes(left_type))
60		return;
61
62	set_state_expr(my_id, expr->left, &too_small);
63}
64
65static void match_dereferences(struct expression *expr)
66{
67	struct symbol *left_type;
68	struct expression *right;
69	struct smatch_state *state;
70	char *name;
71	struct expression *size_expr;
72	sval_t min_size;
73	int limit_type;
74
75	if (expr->type != EXPR_PREOP)
76		return;
77
78	expr = strip_expr(expr->unop);
79	state = get_state_expr(my_id, expr);
80	if (state != &too_small)
81		return;
82
83	left_type = get_type(expr);
84	if (!left_type || left_type->type != SYM_PTR)
85		return;
86	left_type = get_real_base_type(left_type);
87	if (!left_type || left_type->type != SYM_STRUCT)
88		return;
89
90	right = get_assigned_expr(expr);
91	size_expr = get_size_variable(right, &limit_type);
92	if (!size_expr)
93		return;
94	if (limit_type != ELEM_COUNT)
95		return;
96
97	get_absolute_min(size_expr, &min_size);
98	if (min_size.value >= type_bytes(left_type))
99		return;
100
101	name = expr_to_str(right);
102	sm_warning("is '%s' large enough for 'struct %s'? %s", name, left_type->ident ? left_type->ident->name : "<anon>", sval_to_str(min_size));
103	free_string(name);
104	set_state_expr(my_id, expr, &undefined);
105}
106
107void check_buffer_too_small_for_struct(int id)
108{
109	my_id = id;
110
111	add_hook(&match_assign, ASSIGNMENT_HOOK);
112	add_hook(&match_dereferences, DEREF_HOOK);
113}
114