[linux-2.6-block.git] / mm / kasan / report.c

/*
 * 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"
#include "../slab.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 KASAN_FREE_PAGE:
	case KASAN_KMALLOC_FREE:
		bug_type = "use after free";
		break;
	case KASAN_PAGE_REDZONE:
	case KASAN_KMALLOC_REDZONE:
	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)
{
	const void *addr = info->access_addr;

	if ((addr >= (void *)PAGE_OFFSET) &&
		(addr < high_memory)) {
		struct page *page = virt_to_head_page(addr);

		if (PageSlab(page)) {
			void *object;
			struct kmem_cache *cache = page->slab_cache;
			void *last_object;

			object = virt_to_obj(cache, page_address(page), addr);
			last_object = page_address(page) +
				page->objects * cache->size;

			if (unlikely(object > last_object))
				object = last_object; /* we hit into padding */

			object_err(cache, page, object,
				"kasan: bad access detected");
			return;
		}
		dump_page(page, "kasan: bad access detected");
	}

	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);
Commit	Line	Data
0b24becc AR	1	/*
	2	* This file contains error reporting code.
	3	*
	4	* Copyright (c) 2014 Samsung Electronics Co., Ltd.
	5	* Author: Andrey Ryabinin <a.ryabinin@samsung.com>
	6	*
	7	* Some of code borrowed from https://github.com/xairy/linux by
	8	* Andrey Konovalov <adech.fo@gmail.com>
	9	*
	10	* This program is free software; you can redistribute it and/or modify
	11	* it under the terms of the GNU General Public License version 2 as
	12	* published by the Free Software Foundation.
	13	*
	14	*/
	15
	16	#include <linux/kernel.h>
	17	#include <linux/mm.h>
	18	#include <linux/printk.h>
	19	#include <linux/sched.h>
	20	#include <linux/slab.h>
	21	#include <linux/stacktrace.h>
	22	#include <linux/string.h>
	23	#include <linux/types.h>
	24	#include <linux/kasan.h>
	25
	26	#include "kasan.h"
0316bec2	27	#include "../slab.h"
0b24becc AR	28
	29	/* Shadow layout customization. */
	30	#define SHADOW_BYTES_PER_BLOCK 1
	31	#define SHADOW_BLOCKS_PER_ROW 16
	32	#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
	33	#define SHADOW_ROWS_AROUND_ADDR 2
	34
	35	static const void find_first_bad_addr(const void addr, size_t size)
	36	{
	37	u8 shadow_val = (u8 )kasan_mem_to_shadow(addr);
	38	const void *first_bad_addr = addr;
	39
	40	while (!shadow_val && first_bad_addr < addr + size) {
	41	first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
	42	shadow_val = (u8 )kasan_mem_to_shadow(first_bad_addr);
	43	}
	44	return first_bad_addr;
	45	}
	46
	47	static void print_error_description(struct kasan_access_info *info)
	48	{
	49	const char *bug_type = "unknown crash";
	50	u8 shadow_val;
	51
	52	info->first_bad_addr = find_first_bad_addr(info->access_addr,
	53	info->access_size);
	54
	55	shadow_val = (u8 )kasan_mem_to_shadow(info->first_bad_addr);
	56
	57	switch (shadow_val) {
b8c73fc2	58	case KASAN_FREE_PAGE:
0316bec2	59	case KASAN_KMALLOC_FREE:
b8c73fc2 AR	60	bug_type = "use after free";
b8c73fc2 AR	61	break;
0316bec2 AR	62	case KASAN_PAGE_REDZONE:
0316bec2 AR	63	case KASAN_KMALLOC_REDZONE:
0b24becc AR	64	case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
	65	bug_type = "out of bounds access";
	66	break;
	67	}
	68
	69	pr_err("BUG: KASan: %s in %pS at addr %p\n",
	70	bug_type, (void *)info->ip,
	71	info->access_addr);
	72	pr_err("%s of size %zu by task %s/%d\n",
	73	info->is_write ? "Write" : "Read",
	74	info->access_size, current->comm, task_pid_nr(current));
	75	}
	76
	77	static void print_address_description(struct kasan_access_info *info)
	78	{
b8c73fc2 AR	79	const void *addr = info->access_addr;
	80
	81	if ((addr >= (void *)PAGE_OFFSET) &&
	82	(addr < high_memory)) {
	83	struct page *page = virt_to_head_page(addr);
0316bec2 AR	84
	85	if (PageSlab(page)) {
	86	void *object;
	87	struct kmem_cache *cache = page->slab_cache;
	88	void *last_object;
	89
	90	object = virt_to_obj(cache, page_address(page), addr);
	91	last_object = page_address(page) +
	92	page->objects * cache->size;
	93
	94	if (unlikely(object > last_object))
	95	object = last_object; /* we hit into padding */
	96
	97	object_err(cache, page, object,
	98	"kasan: bad access detected");
	99	return;
	100	}
b8c73fc2 AR	101	dump_page(page, "kasan: bad access detected");
	102	}
	103
0b24becc AR	104	dump_stack();
	105	}
	106
	107	static bool row_is_guilty(const void row, const void guilty)
	108	{
	109	return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
	110	}
	111
	112	static int shadow_pointer_offset(const void row, const void shadow)
	113	{
	114	/* The length of ">ff00ff00ff00ff00: " is
	115	* 3 + (BITS_PER_LONG/8)*2 chars.
	116	*/
	117	return 3 + (BITS_PER_LONG/8)2 + (shadow - row)2 +
	118	(shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
	119	}
	120
	121	static void print_shadow_for_address(const void *addr)
	122	{
	123	int i;
	124	const void *shadow = kasan_mem_to_shadow(addr);
	125	const void *shadow_row;
	126
	127	shadow_row = (void *)round_down((unsigned long)shadow,
	128	SHADOW_BYTES_PER_ROW)
	129	- SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
	130
	131	pr_err("Memory state around the buggy address:\n");
	132
	133	for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
	134	const void *kaddr = kasan_shadow_to_mem(shadow_row);
	135	char buffer[4 + (BITS_PER_LONG/8)*2];
	136
	137	snprintf(buffer, sizeof(buffer),
	138	(i == 0) ? ">%p: " : " %p: ", kaddr);
	139
	140	kasan_disable_current();
	141	print_hex_dump(KERN_ERR, buffer,
	142	DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
	143	shadow_row, SHADOW_BYTES_PER_ROW, 0);
	144	kasan_enable_current();
	145
	146	if (row_is_guilty(shadow_row, shadow))
	147	pr_err("%*c\n",
	148	shadow_pointer_offset(shadow_row, shadow),
	149	'^');
	150
	151	shadow_row += SHADOW_BYTES_PER_ROW;
	152	}
	153	}
	154
	155	static DEFINE_SPINLOCK(report_lock);
	156
	157	void kasan_report_error(struct kasan_access_info *info)
	158	{
	159	unsigned long flags;
	160
	161	spin_lock_irqsave(&report_lock, flags);
	162	pr_err("================================="
	163	"=================================\n");
	164	print_error_description(info);
	165	print_address_description(info);
	166	print_shadow_for_address(info->first_bad_addr);
	167	pr_err("================================="
168	"=================================\n");
169	spin_unlock_irqrestore(&report_lock, flags);
170	}
171
172	void kasan_report_user_access(struct kasan_access_info *info)
173	{
174	unsigned long flags;
175
176	spin_lock_irqsave(&report_lock, flags);
177	pr_err("================================="
178	"=================================\n");
179	pr_err("BUG: KASan: user-memory-access on address %p\n",
180	info->access_addr);
181	pr_err("%s of size %zu by task %s/%d\n",
182	info->is_write ? "Write" : "Read",
183	info->access_size, current->comm, task_pid_nr(current));
184	dump_stack();
185	pr_err("================================="
186	"=================================\n");
187	spin_unlock_irqrestore(&report_lock, flags);
188	}
189
190	void kasan_report(unsigned long addr, size_t size,
191	bool is_write, unsigned long ip)
192	{
193	struct kasan_access_info info;
194
195	if (likely(!kasan_enabled()))
196	return;
197
198	info.access_addr = (void *)addr;
199	info.access_size = size;
200	info.is_write = is_write;
201	info.ip = ip;
202	kasan_report_error(&info);
203	}
204
205
206	#define DEFINE_ASAN_REPORT_LOAD(size) \
207	void __asan_report_load##size##_noabort(unsigned long addr) \
208	{ \
209	kasan_report(addr, size, false, _RET_IP_); \
210	} \
211	EXPORT_SYMBOL(__asan_report_load##size##_noabort)
212
213	#define DEFINE_ASAN_REPORT_STORE(size) \
214	void __asan_report_store##size##_noabort(unsigned long addr) \
215	{ \
216	kasan_report(addr, size, true, _RET_IP_); \
217	} \
218	EXPORT_SYMBOL(__asan_report_store##size##_noabort)
219
220	DEFINE_ASAN_REPORT_LOAD(1);
221	DEFINE_ASAN_REPORT_LOAD(2);
222	DEFINE_ASAN_REPORT_LOAD(4);
223	DEFINE_ASAN_REPORT_LOAD(8);
224	DEFINE_ASAN_REPORT_LOAD(16);
225	DEFINE_ASAN_REPORT_STORE(1);
226	DEFINE_ASAN_REPORT_STORE(2);
227	DEFINE_ASAN_REPORT_STORE(4);
228	DEFINE_ASAN_REPORT_STORE(8);
229	DEFINE_ASAN_REPORT_STORE(16);
230
231	void __asan_report_load_n_noabort(unsigned long addr, size_t size)
232	{
233	kasan_report(addr, size, false, _RET_IP_);
234	}
235	EXPORT_SYMBOL(__asan_report_load_n_noabort);
236
237	void __asan_report_store_n_noabort(unsigned long addr, size_t size)
238	{
239	kasan_report(addr, size, true, _RET_IP_);
240	}
241	EXPORT_SYMBOL(__asan_report_store_n_noabort);