aboutsummaryrefslogtreecommitdiffstats
path: root/mm/kasan/report.c
blob: 5835d69563f556751435e28dc6b63478653a732d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
/*
 * This file contains error reporting code.
 *
 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
 * Author: Andrey Ryabinin <a.ryabinin@samsung.com>
 *
 * Some of code borrowed from https://github.com/xairy/linux by
 *        Andrey Konovalov <adech.fo@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/printk.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/stacktrace.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/kasan.h>

#include "kasan.h"

/* Shadow layout customization. */
#define SHADOW_BYTES_PER_BLOCK 1
#define SHADOW_BLOCKS_PER_ROW 16
#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
#define SHADOW_ROWS_AROUND_ADDR 2

static const void *find_first_bad_addr(const void *addr, size_t size)
{
	u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
	const void *first_bad_addr = addr;

	while (!shadow_val && first_bad_addr < addr + size) {
		first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
		shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
	}
	return first_bad_addr;
}

static void print_error_description(struct kasan_access_info *info)
{
	const char *bug_type = "unknown crash";
	u8 shadow_val;

	info->first_bad_addr = find_first_bad_addr(info->access_addr,
						info->access_size);

	shadow_val = *(u8 *)kasan_mem_to_shadow(info->first_bad_addr);

	switch (shadow_val) {
	case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
		bug_type = "out of bounds access";
		break;
	}

	pr_err("BUG: KASan: %s in %pS at addr %p\n",
		bug_type, (void *)info->ip,
		info->access_addr);
	pr_err("%s of size %zu by task %s/%d\n",
		info->is_write ? "Write" : "Read",
		info->access_size, current->comm, task_pid_nr(current));
}

static void print_address_description(struct kasan_access_info *info)
{
	dump_stack();
}

static bool row_is_guilty(const void *row, const void *guilty)
{
	return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
}

static int shadow_pointer_offset(const void *row, const void *shadow)
{
	/* The length of ">ff00ff00ff00ff00: " is
	 *    3 + (BITS_PER_LONG/8)*2 chars.
	 */
	return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
		(shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
}

static void print_shadow_for_address(const void *addr)
{
	int i;
	const void *shadow = kasan_mem_to_shadow(addr);
	const void *shadow_row;

	shadow_row = (void *)round_down((unsigned long)shadow,
					SHADOW_BYTES_PER_ROW)
		- SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;

	pr_err("Memory state around the buggy address:\n");

	for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
		const void *kaddr = kasan_shadow_to_mem(shadow_row);
		char buffer[4 + (BITS_PER_LONG/8)*2];

		snprintf(buffer, sizeof(buffer),
			(i == 0) ? ">%p: " : " %p: ", kaddr);

		kasan_disable_current();
		print_hex_dump(KERN_ERR, buffer,
			DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
			shadow_row, SHADOW_BYTES_PER_ROW, 0);
		kasan_enable_current();

		if (row_is_guilty(shadow_row, shadow))
			pr_err("%*c\n",
				shadow_pointer_offset(shadow_row, shadow),
				'^');

		shadow_row += SHADOW_BYTES_PER_ROW;
	}
}

static DEFINE_SPINLOCK(report_lock);

void kasan_report_error(struct kasan_access_info *info)
{
	unsigned long flags;

	spin_lock_irqsave(&report_lock, flags);
	pr_err("================================="
		"=================================\n");
	print_error_description(info);
	print_address_description(info);
	print_shadow_for_address(info->first_bad_addr);
	pr_err("================================="
		"=================================\n");
	spin_unlock_irqrestore(&report_lock, flags);
}

void kasan_report_user_access(struct kasan_access_info *info)
{
	unsigned long flags;

	spin_lock_irqsave(&report_lock, flags);
	pr_err("================================="
		"=================================\n");
	pr_err("BUG: KASan: user-memory-access on address %p\n",
		info->access_addr);
	pr_err("%s of size %zu by task %s/%d\n",
		info->is_write ? "Write" : "Read",
		info->access_size, current->comm, task_pid_nr(current));
	dump_stack();
	pr_err("================================="
		"=================================\n");
	spin_unlock_irqrestore(&report_lock, flags);
}

void kasan_report(unsigned long addr, size_t size,
		bool is_write, unsigned long ip)
{
	struct kasan_access_info info;

	if (likely(!kasan_enabled()))
		return;

	info.access_addr = (void *)addr;
	info.access_size = size;
	info.is_write = is_write;
	info.ip = ip;
	kasan_report_error(&info);
}


#define DEFINE_ASAN_REPORT_LOAD(size)                     \
void __asan_report_load##size##_noabort(unsigned long addr) \
{                                                         \
	kasan_report(addr, size, false, _RET_IP_);	  \
}                                                         \
EXPORT_SYMBOL(__asan_report_load##size##_noabort)

#define DEFINE_ASAN_REPORT_STORE(size)                     \
void __asan_report_store##size##_noabort(unsigned long addr) \
{                                                          \
	kasan_report(addr, size, true, _RET_IP_);	   \
}                                                          \
EXPORT_SYMBOL(__asan_report_store##size##_noabort)

DEFINE_ASAN_REPORT_LOAD(1);
DEFINE_ASAN_REPORT_LOAD(2);
DEFINE_ASAN_REPORT_LOAD(4);
DEFINE_ASAN_REPORT_LOAD(8);
DEFINE_ASAN_REPORT_LOAD(16);
DEFINE_ASAN_REPORT_STORE(1);
DEFINE_ASAN_REPORT_STORE(2);
DEFINE_ASAN_REPORT_STORE(4);
DEFINE_ASAN_REPORT_STORE(8);
DEFINE_ASAN_REPORT_STORE(16);

void __asan_report_load_n_noabort(unsigned long addr, size_t size)
{
	kasan_report(addr, size, false, _RET_IP_);
}
EXPORT_SYMBOL(__asan_report_load_n_noabort);

void __asan_report_store_n_noabort(unsigned long addr, size_t size)
{
	kasan_report(addr, size, true, _RET_IP_);
}
EXPORT_SYMBOL(__asan_report_store_n_noabort);

Privacy Policy