[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 <ryabinin.a.a@gmail.com>
 *
 * Some code borrowed from https://github.com/xairy/kasan-prototype 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 <linux/module.h>

#include <asm/sections.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_addr;

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

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

	/*
	 * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
	 * at the next shadow byte to determine the type of the bad access.
	 */
	if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
		shadow_addr++;

	switch (*shadow_addr) {
	case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
		/*
		 * In theory it's still possible to see these shadow values
		 * due to a data race in the kernel code.
		 */
		bug_type = "out-of-bounds";
		break;
	case KASAN_PAGE_REDZONE:
	case KASAN_KMALLOC_REDZONE:
		bug_type = "slab-out-of-bounds";
		break;
	case KASAN_GLOBAL_REDZONE:
		bug_type = "global-out-of-bounds";
		break;
	case KASAN_STACK_LEFT:
	case KASAN_STACK_MID:
	case KASAN_STACK_RIGHT:
	case KASAN_STACK_PARTIAL:
		bug_type = "stack-out-of-bounds";
		break;
	case KASAN_FREE_PAGE:
	case KASAN_KMALLOC_FREE:
		bug_type = "use-after-free";
		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 inline bool kernel_or_module_addr(const void *addr)
{
	if (addr >= (void *)_stext && addr < (void *)_end)
		return true;
	if (is_module_address((unsigned long)addr))
		return true;
	return false;
}

static inline bool init_task_stack_addr(const void *addr)
{
	return addr >= (void *)&init_thread_union.stack &&
		(addr <= (void *)&init_thread_union.stack +
			sizeof(init_thread_union.stack));
}

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");
	}

	if (kernel_or_module_addr(addr)) {
		if (!init_task_stack_addr(addr))
			pr_err("Address belongs to variable %pS\n", addr);
	}

	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];
		char shadow_buf[SHADOW_BYTES_PER_ROW];

		snprintf(buffer, sizeof(buffer),
			(i == 0) ? ">%p: " : " %p: ", kaddr);
		/*
		 * We should not pass a shadow pointer to generic
		 * function, because generic functions may try to
		 * access kasan mapping for the passed address.
		 */
		memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
		print_hex_dump(KERN_ERR, buffer,
			DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
			shadow_buf, SHADOW_BYTES_PER_ROW, 0);

		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);

static void kasan_report_error(struct kasan_access_info *info)
{
	unsigned long flags;
	const char *bug_type;

	/*
	 * Make sure we don't end up in loop.
	 */
	kasan_disable_current();
	spin_lock_irqsave(&report_lock, flags);
	pr_err("==================================================================\n");
	if (info->access_addr <
			kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
		if ((unsigned long)info->access_addr < PAGE_SIZE)
			bug_type = "null-ptr-deref";
		else if ((unsigned long)info->access_addr < TASK_SIZE)
			bug_type = "user-memory-access";
		else
			bug_type = "wild-memory-access";
		pr_err("BUG: KASAN: %s on address %p\n",
			bug_type, 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();
	} else {
		print_error_description(info);
		print_address_description(info);
		print_shadow_for_address(info->first_bad_addr);
	}
	pr_err("==================================================================\n");
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
	spin_unlock_irqrestore(&report_lock, flags);
	kasan_enable_current();
}

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

	if (likely(!kasan_report_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.
2baf9e89	5	* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
0b24becc	6	*
5d0926ef	7	* Some code borrowed from https://github.com/xairy/kasan-prototype by
0b24becc AR	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>
527f215b	25	#include <linux/module.h>
0b24becc	26
bebf56a1 AR	27	#include <asm/sections.h>
bebf56a1 AR	28
0b24becc	29	#include "kasan.h"
0316bec2	30	#include "../slab.h"
0b24becc AR	31
	32	/* Shadow layout customization. */
	33	#define SHADOW_BYTES_PER_BLOCK 1
	34	#define SHADOW_BLOCKS_PER_ROW 16
	35	#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
	36	#define SHADOW_ROWS_AROUND_ADDR 2
	37
	38	static const void find_first_bad_addr(const void addr, size_t size)
	39	{
	40	u8 shadow_val = (u8 )kasan_mem_to_shadow(addr);
	41	const void *first_bad_addr = addr;
	42
	43	while (!shadow_val && first_bad_addr < addr + size) {
	44	first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
	45	shadow_val = (u8 )kasan_mem_to_shadow(first_bad_addr);
	46	}
	47	return first_bad_addr;
	48	}
	49
	50	static void print_error_description(struct kasan_access_info *info)
	51	{
0952d87f	52	const char *bug_type = "unknown-crash";
cdf6a273	53	u8 *shadow_addr;
0b24becc AR	54
	55	info->first_bad_addr = find_first_bad_addr(info->access_addr,
	56	info->access_size);
	57
cdf6a273	58	shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
0b24becc	59
cdf6a273 AK	60	/*
	61	* If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
	62	* at the next shadow byte to determine the type of the bad access.
	63	*/
	64	if (shadow_addr > 0 && shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
	65	shadow_addr++;
	66
	67	switch (*shadow_addr) {
0952d87f	68	case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
cdf6a273 AK	69	/*
	70	* In theory it's still possible to see these shadow values
	71	* due to a data race in the kernel code.
	72	*/
0952d87f	73	bug_type = "out-of-bounds";
b8c73fc2	74	break;
0316bec2 AR	75	case KASAN_PAGE_REDZONE:
0316bec2 AR	76	case KASAN_KMALLOC_REDZONE:
0952d87f AK	77	bug_type = "slab-out-of-bounds";
0952d87f AK	78	break;
bebf56a1	79	case KASAN_GLOBAL_REDZONE:
0952d87f	80	bug_type = "global-out-of-bounds";
0b24becc	81	break;
c420f167 AR	82	case KASAN_STACK_LEFT:
	83	case KASAN_STACK_MID:
	84	case KASAN_STACK_RIGHT:
	85	case KASAN_STACK_PARTIAL:
0952d87f AK	86	bug_type = "stack-out-of-bounds";
	87	break;
	88	case KASAN_FREE_PAGE:
	89	case KASAN_KMALLOC_FREE:
	90	bug_type = "use-after-free";
c420f167	91	break;
0b24becc AR	92	}
0b24becc AR	93
25add7ec	94	pr_err("BUG: KASAN: %s in %pS at addr %p\n",
0b24becc AR	95	bug_type, (void *)info->ip,
	96	info->access_addr);
	97	pr_err("%s of size %zu by task %s/%d\n",
	98	info->is_write ? "Write" : "Read",
	99	info->access_size, current->comm, task_pid_nr(current));
	100	}
	101
bebf56a1 AR	102	static inline bool kernel_or_module_addr(const void *addr)
bebf56a1 AR	103	{
527f215b AK	104	if (addr >= (void )_stext && addr < (void )_end)
	105	return true;
	106	if (is_module_address((unsigned long)addr))
	107	return true;
	108	return false;
bebf56a1 AR	109	}
	110
	111	static inline bool init_task_stack_addr(const void *addr)
	112	{
	113	return addr >= (void *)&init_thread_union.stack &&
	114	(addr <= (void *)&init_thread_union.stack +
	115	sizeof(init_thread_union.stack));
	116	}
	117
0b24becc AR	118	static void print_address_description(struct kasan_access_info *info)
0b24becc AR	119	{
b8c73fc2 AR	120	const void *addr = info->access_addr;
	121
	122	if ((addr >= (void *)PAGE_OFFSET) &&
	123	(addr < high_memory)) {
	124	struct page *page = virt_to_head_page(addr);
0316bec2 AR	125
	126	if (PageSlab(page)) {
	127	void *object;
	128	struct kmem_cache *cache = page->slab_cache;
	129	void *last_object;
	130
	131	object = virt_to_obj(cache, page_address(page), addr);
	132	last_object = page_address(page) +
	133	page->objects * cache->size;
	134
	135	if (unlikely(object > last_object))
	136	object = last_object; /* we hit into padding */
	137
	138	object_err(cache, page, object,
	139	"kasan: bad access detected");
	140	return;
	141	}
b8c73fc2 AR	142	dump_page(page, "kasan: bad access detected");
	143	}
	144
bebf56a1 AR	145	if (kernel_or_module_addr(addr)) {
	146	if (!init_task_stack_addr(addr))
	147	pr_err("Address belongs to variable %pS\n", addr);
	148	}
	149
0b24becc AR	150	dump_stack();
	151	}
	152
	153	static bool row_is_guilty(const void row, const void guilty)
	154	{
	155	return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
	156	}
	157
	158	static int shadow_pointer_offset(const void row, const void shadow)
	159	{
	160	/* The length of ">ff00ff00ff00ff00: " is
	161	* 3 + (BITS_PER_LONG/8)*2 chars.
	162	*/
	163	return 3 + (BITS_PER_LONG/8)2 + (shadow - row)2 +
	164	(shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
	165	}
	166
	167	static void print_shadow_for_address(const void *addr)
	168	{
	169	int i;
	170	const void *shadow = kasan_mem_to_shadow(addr);
	171	const void *shadow_row;
	172
	173	shadow_row = (void *)round_down((unsigned long)shadow,
	174	SHADOW_BYTES_PER_ROW)
	175	- SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
	176
	177	pr_err("Memory state around the buggy address:\n");
	178
	179	for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
	180	const void *kaddr = kasan_shadow_to_mem(shadow_row);
	181	char buffer[4 + (BITS_PER_LONG/8)*2];
f2377d4e	182	char shadow_buf[SHADOW_BYTES_PER_ROW];
0b24becc AR	183
	184	snprintf(buffer, sizeof(buffer),
	185	(i == 0) ? ">%p: " : " %p: ", kaddr);
f2377d4e AK	186	/*
	187	* We should not pass a shadow pointer to generic
	188	* function, because generic functions may try to
	189	* access kasan mapping for the passed address.
	190	*/
f2377d4e	191	memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
0b24becc AR	192	print_hex_dump(KERN_ERR, buffer,
0b24becc AR	193	DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
f2377d4e	194	shadow_buf, SHADOW_BYTES_PER_ROW, 0);
0b24becc AR	195
	196	if (row_is_guilty(shadow_row, shadow))
	197	pr_err("%*c\n",
	198	shadow_pointer_offset(shadow_row, shadow),
	199	'^');
	200
	201	shadow_row += SHADOW_BYTES_PER_ROW;
	202	}
	203	}
	204
	205	static DEFINE_SPINLOCK(report_lock);
	206
e9121076	207	static void kasan_report_error(struct kasan_access_info *info)
0b24becc AR	208	{
0b24becc AR	209	unsigned long flags;
e9121076	210	const char *bug_type;
0b24becc	211
fc5aeeaf AK	212	/*
	213	* Make sure we don't end up in loop.
	214	*/
	215	kasan_disable_current();
0b24becc	216	spin_lock_irqsave(&report_lock, flags);
756a025f	217	pr_err("==================================================================\n");
e9121076 AK	218	if (info->access_addr <
	219	kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
	220	if ((unsigned long)info->access_addr < PAGE_SIZE)
	221	bug_type = "null-ptr-deref";
	222	else if ((unsigned long)info->access_addr < TASK_SIZE)
	223	bug_type = "user-memory-access";
	224	else
	225	bug_type = "wild-memory-access";
25add7ec	226	pr_err("BUG: KASAN: %s on address %p\n",
e9121076 AK	227	bug_type, info->access_addr);
	228	pr_err("%s of size %zu by task %s/%d\n",
	229	info->is_write ? "Write" : "Read",
	230	info->access_size, current->comm,
	231	task_pid_nr(current));
	232	dump_stack();
	233	} else {
	234	print_error_description(info);
	235	print_address_description(info);
	236	print_shadow_for_address(info->first_bad_addr);
	237	}
756a025f	238	pr_err("==================================================================\n");
eb06f43f	239	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
0b24becc	240	spin_unlock_irqrestore(&report_lock, flags);
fc5aeeaf	241	kasan_enable_current();
0b24becc AR	242	}
	243
	244	void kasan_report(unsigned long addr, size_t size,
	245	bool is_write, unsigned long ip)
	246	{
	247	struct kasan_access_info info;
	248
0ba8663c	249	if (likely(!kasan_report_enabled()))
0b24becc AR	250	return;
	251
	252	info.access_addr = (void *)addr;
	253	info.access_size = size;
	254	info.is_write = is_write;
	255	info.ip = ip;
e9121076	256
0b24becc AR	257	kasan_report_error(&info);
	258	}
	259
	260
	261	#define DEFINE_ASAN_REPORT_LOAD(size) \
	262	void __asan_report_load##size##_noabort(unsigned long addr) \
	263	{ \
	264	kasan_report(addr, size, false, _RET_IP_); \
	265	} \
	266	EXPORT_SYMBOL(__asan_report_load##size##_noabort)
	267
	268	#define DEFINE_ASAN_REPORT_STORE(size) \
	269	void __asan_report_store##size##_noabort(unsigned long addr) \
	270	{ \
	271	kasan_report(addr, size, true, _RET_IP_); \
	272	} \
	273	EXPORT_SYMBOL(__asan_report_store##size##_noabort)
	274
	275	DEFINE_ASAN_REPORT_LOAD(1);
	276	DEFINE_ASAN_REPORT_LOAD(2);
	277	DEFINE_ASAN_REPORT_LOAD(4);
	278	DEFINE_ASAN_REPORT_LOAD(8);
	279	DEFINE_ASAN_REPORT_LOAD(16);
	280	DEFINE_ASAN_REPORT_STORE(1);
	281	DEFINE_ASAN_REPORT_STORE(2);
	282	DEFINE_ASAN_REPORT_STORE(4);
	283	DEFINE_ASAN_REPORT_STORE(8);
	284	DEFINE_ASAN_REPORT_STORE(16);
	285
	286	void __asan_report_load_n_noabort(unsigned long addr, size_t size)
	287	{
	288	kasan_report(addr, size, false, _RET_IP_);
	289	}
	290	EXPORT_SYMBOL(__asan_report_load_n_noabort);
	291
	292	void __asan_report_store_n_noabort(unsigned long addr, size_t size)
	293	{
	294	kasan_report(addr, size, true, _RET_IP_);
	295	}
	296	EXPORT_SYMBOL(__asan_report_store_n_noabort);