[mirror_ubuntu-artful-kernel.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/bitops.h>
#include <linux/ftrace.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/printk.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/stackdepot.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 bool addr_has_shadow(struct kasan_access_info *info)
{
	return (info->access_addr >=
		kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
}

static const char *get_shadow_bug_type(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;
	case KASAN_USE_AFTER_SCOPE:
		bug_type = "use-after-scope";
		break;
	}

	return bug_type;
}

static const char *get_wild_bug_type(struct kasan_access_info *info)
{
	const char *bug_type = "unknown-crash";

	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";

	return bug_type;
}

static const char *get_bug_type(struct kasan_access_info *info)
{
	if (addr_has_shadow(info))
		return get_shadow_bug_type(info);
	return get_wild_bug_type(info);
}

static void print_error_description(struct kasan_access_info *info)
{
	const char *bug_type = get_bug_type(info);

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

static void kasan_start_report(unsigned long *flags)
{
	/*
	 * Make sure we don't end up in loop.
	 */
	kasan_disable_current();
	spin_lock_irqsave(&report_lock, *flags);
	pr_err("==================================================================\n");
}

static void kasan_end_report(unsigned long *flags)
{
	pr_err("==================================================================\n");
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
	spin_unlock_irqrestore(&report_lock, *flags);
	if (panic_on_warn)
		panic("panic_on_warn set ...\n");
	kasan_enable_current();
}

static void print_track(struct kasan_track *track, const char *prefix)
{
	pr_err("%s by task %u:\n", prefix, track->pid);
	if (track->stack) {
		struct stack_trace trace;

		depot_fetch_stack(track->stack, &trace);
		print_stack_trace(&trace, 0);
	} else {
		pr_err("(stack is not available)\n");
	}
}

static struct page *addr_to_page(const void *addr)
{
	if ((addr >= (void *)PAGE_OFFSET) &&
			(addr < high_memory))
		return virt_to_head_page(addr);
	return NULL;
}

static void describe_object_addr(struct kmem_cache *cache, void *object,
				const void *addr)
{
	unsigned long access_addr = (unsigned long)addr;
	unsigned long object_addr = (unsigned long)object;
	const char *rel_type;
	int rel_bytes;

	pr_err("The buggy address belongs to the object at %p\n"
	       " which belongs to the cache %s of size %d\n",
		object, cache->name, cache->object_size);

	if (!addr)
		return;

	if (access_addr < object_addr) {
		rel_type = "to the left";
		rel_bytes = object_addr - access_addr;
	} else if (access_addr >= object_addr + cache->object_size) {
		rel_type = "to the right";
		rel_bytes = access_addr - (object_addr + cache->object_size);
	} else {
		rel_type = "inside";
		rel_bytes = access_addr - object_addr;
	}

	pr_err("The buggy address is located %d bytes %s of\n"
	       " %d-byte region [%p, %p)\n",
		rel_bytes, rel_type, cache->object_size, (void *)object_addr,
		(void *)(object_addr + cache->object_size));
}

static void describe_object(struct kmem_cache *cache, void *object,
				const void *addr)
{
	struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);

	if (cache->flags & SLAB_KASAN) {
		print_track(&alloc_info->alloc_track, "Allocated");
		pr_err("\n");
		print_track(&alloc_info->free_track, "Freed");
		pr_err("\n");
	}

	describe_object_addr(cache, object, addr);
}

static void print_address_description(void *addr)
{
	struct page *page = addr_to_page(addr);

	dump_stack();
	pr_err("\n");

	if (page && PageSlab(page)) {
		struct kmem_cache *cache = page->slab_cache;
		void *object = nearest_obj(cache, page,	addr);

		describe_object(cache, object, addr);
	}

	if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) {
		pr_err("The buggy address belongs to the variable:\n");
		pr_err(" %pS\n", addr);
	}

	if (page) {
		pr_err("The buggy address belongs to the page:\n");
		dump_page(page, "kasan: bad access detected");
	}
}

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;
	}
}

void kasan_report_double_free(struct kmem_cache *cache, void *object,
				void *ip)
{
	unsigned long flags;

	kasan_start_report(&flags);
	pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", ip);
	pr_err("\n");
	print_address_description(object);
	pr_err("\n");
	print_shadow_for_address(object);
	kasan_end_report(&flags);
}

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

	kasan_start_report(&flags);

	print_error_description(info);
	pr_err("\n");

	if (!addr_has_shadow(info)) {
		dump_stack();
	} else {
		print_address_description((void *)info->access_addr);
		pr_err("\n");
		print_shadow_for_address(info->first_bad_addr);
	}

	kasan_end_report(&flags);
}

static unsigned long kasan_flags;

#define KASAN_BIT_REPORTED	0
#define KASAN_BIT_MULTI_SHOT	1

bool kasan_save_enable_multi_shot(void)
{
	return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
}
EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot);

void kasan_restore_multi_shot(bool enabled)
{
	if (!enabled)
		clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
}
EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);

static int __init kasan_set_multi_shot(char *str)
{
	set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
	return 1;
}
__setup("kasan_multi_shot", kasan_set_multi_shot);

static inline bool kasan_report_enabled(void)
{
	if (current->kasan_depth)
		return false;
	if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
		return true;
	return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
}

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;

	disable_trace_on_warning();

	info.access_addr = (void *)addr;
	info.first_bad_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
b0845ce5	16	#include <linux/bitops.h>
4f40c6e5	17	#include <linux/ftrace.h>
b0845ce5	18	#include <linux/init.h>
0b24becc AR	19	#include <linux/kernel.h>
	20	#include <linux/mm.h>
	21	#include <linux/printk.h>
	22	#include <linux/sched.h>
	23	#include <linux/slab.h>
cd11016e	24	#include <linux/stackdepot.h>
0b24becc AR	25	#include <linux/stacktrace.h>
	26	#include <linux/string.h>
	27	#include <linux/types.h>
	28	#include <linux/kasan.h>
527f215b	29	#include <linux/module.h>
0b24becc	30
bebf56a1 AR	31	#include <asm/sections.h>
bebf56a1 AR	32
0b24becc	33	#include "kasan.h"
0316bec2	34	#include "../slab.h"
0b24becc AR	35
	36	/* Shadow layout customization. */
	37	#define SHADOW_BYTES_PER_BLOCK 1
	38	#define SHADOW_BLOCKS_PER_ROW 16
	39	#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
	40	#define SHADOW_ROWS_AROUND_ADDR 2
	41
	42	static const void find_first_bad_addr(const void addr, size_t size)
	43	{
	44	u8 shadow_val = (u8 )kasan_mem_to_shadow(addr);
	45	const void *first_bad_addr = addr;
	46
	47	while (!shadow_val && first_bad_addr < addr + size) {
	48	first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
	49	shadow_val = (u8 )kasan_mem_to_shadow(first_bad_addr);
	50	}
	51	return first_bad_addr;
	52	}
	53
5e82cd12 AK	54	static bool addr_has_shadow(struct kasan_access_info *info)
	55	{
	56	return (info->access_addr >=
	57	kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
	58	}
	59
	60	static const char get_shadow_bug_type(struct kasan_access_info info)
0b24becc	61	{
0952d87f	62	const char *bug_type = "unknown-crash";
cdf6a273	63	u8 *shadow_addr;
0b24becc AR	64
	65	info->first_bad_addr = find_first_bad_addr(info->access_addr,
	66	info->access_size);
	67
cdf6a273	68	shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
0b24becc	69
cdf6a273 AK	70	/*
	71	* If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
	72	* at the next shadow byte to determine the type of the bad access.
	73	*/
	74	if (shadow_addr > 0 && shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
	75	shadow_addr++;
	76
	77	switch (*shadow_addr) {
0952d87f	78	case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
cdf6a273 AK	79	/*
	80	* In theory it's still possible to see these shadow values
	81	* due to a data race in the kernel code.
	82	*/
0952d87f	83	bug_type = "out-of-bounds";
b8c73fc2	84	break;
0316bec2 AR	85	case KASAN_PAGE_REDZONE:
0316bec2 AR	86	case KASAN_KMALLOC_REDZONE:
0952d87f AK	87	bug_type = "slab-out-of-bounds";
0952d87f AK	88	break;
bebf56a1	89	case KASAN_GLOBAL_REDZONE:
0952d87f	90	bug_type = "global-out-of-bounds";
0b24becc	91	break;
c420f167 AR	92	case KASAN_STACK_LEFT:
	93	case KASAN_STACK_MID:
	94	case KASAN_STACK_RIGHT:
	95	case KASAN_STACK_PARTIAL:
0952d87f AK	96	bug_type = "stack-out-of-bounds";
	97	break;
	98	case KASAN_FREE_PAGE:
	99	case KASAN_KMALLOC_FREE:
	100	bug_type = "use-after-free";
c420f167	101	break;
828347f8 DV	102	case KASAN_USE_AFTER_SCOPE:
	103	bug_type = "use-after-scope";
	104	break;
0b24becc AR	105	}
0b24becc AR	106
5e82cd12 AK	107	return bug_type;
	108	}
	109
822d5ec2	110	static const char get_wild_bug_type(struct kasan_access_info info)
5e82cd12 AK	111	{
	112	const char *bug_type = "unknown-crash";
	113
	114	if ((unsigned long)info->access_addr < PAGE_SIZE)
	115	bug_type = "null-ptr-deref";
	116	else if ((unsigned long)info->access_addr < TASK_SIZE)
	117	bug_type = "user-memory-access";
	118	else
	119	bug_type = "wild-memory-access";
	120
	121	return bug_type;
	122	}
	123
7d418f7b AK	124	static const char get_bug_type(struct kasan_access_info info)
	125	{
	126	if (addr_has_shadow(info))
	127	return get_shadow_bug_type(info);
	128	return get_wild_bug_type(info);
	129	}
	130
5e82cd12 AK	131	static void print_error_description(struct kasan_access_info *info)
5e82cd12 AK	132	{
7d418f7b	133	const char *bug_type = get_bug_type(info);
5e82cd12	134
7f0a84c2 AK	135	pr_err("BUG: KASAN: %s in %pS\n",
	136	bug_type, (void *)info->ip);
	137	pr_err("%s of size %zu at addr %p by task %s/%d\n",
7d418f7b	138	info->is_write ? "Write" : "Read", info->access_size,
7f0a84c2	139	info->access_addr, current->comm, task_pid_nr(current));
0b24becc AR	140	}
0b24becc AR	141
bebf56a1 AR	142	static inline bool kernel_or_module_addr(const void *addr)
bebf56a1 AR	143	{
527f215b AK	144	if (addr >= (void )_stext && addr < (void )_end)
	145	return true;
	146	if (is_module_address((unsigned long)addr))
	147	return true;
	148	return false;
bebf56a1 AR	149	}
	150
	151	static inline bool init_task_stack_addr(const void *addr)
	152	{
	153	return addr >= (void *)&init_thread_union.stack &&
	154	(addr <= (void *)&init_thread_union.stack +
	155	sizeof(init_thread_union.stack));
	156	}
	157
7e088978 AR	158	static DEFINE_SPINLOCK(report_lock);
	159
	160	static void kasan_start_report(unsigned long *flags)
	161	{
	162	/*
	163	* Make sure we don't end up in loop.
	164	*/
	165	kasan_disable_current();
	166	spin_lock_irqsave(&report_lock, *flags);
	167	pr_err("==================================================================\n");
	168	}
	169
	170	static void kasan_end_report(unsigned long *flags)
	171	{
	172	pr_err("==================================================================\n");
	173	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
	174	spin_unlock_irqrestore(&report_lock, *flags);
5c5c1f36 DV	175	if (panic_on_warn)
5c5c1f36 DV	176	panic("panic_on_warn set ...\n");
7e088978 AR	177	kasan_enable_current();
	178	}
	179
b6b72f49	180	static void print_track(struct kasan_track track, const char prefix)
7ed2f9e6	181	{
b6b72f49	182	pr_err("%s by task %u:\n", prefix, track->pid);
cd11016e AP	183	if (track->stack) {
	184	struct stack_trace trace;
	185
	186	depot_fetch_stack(track->stack, &trace);
	187	print_stack_trace(&trace, 0);
	188	} else {
	189	pr_err("(stack is not available)\n");
	190	}
7ed2f9e6 AP	191	}
7ed2f9e6 AP	192
db429f16 AK	193	static struct page addr_to_page(const void addr)
	194	{
	195	if ((addr >= (void *)PAGE_OFFSET) &&
	196	(addr < high_memory))
	197	return virt_to_head_page(addr);
	198	return NULL;
	199	}
	200
0c06f1f8 AK	201	static void describe_object_addr(struct kmem_cache cache, void object,
0c06f1f8 AK	202	const void *addr)
7ed2f9e6	203	{
0c06f1f8 AK	204	unsigned long access_addr = (unsigned long)addr;
	205	unsigned long object_addr = (unsigned long)object;
	206	const char *rel_type;
	207	int rel_bytes;
7ed2f9e6	208
0c06f1f8 AK	209	pr_err("The buggy address belongs to the object at %p\n"
	210	" which belongs to the cache %s of size %d\n",
	211	object, cache->name, cache->object_size);
47b5c2a0	212
0c06f1f8	213	if (!addr)
7ed2f9e6	214	return;
b3cbd9bf	215
0c06f1f8 AK	216	if (access_addr < object_addr) {
	217	rel_type = "to the left";
	218	rel_bytes = object_addr - access_addr;
	219	} else if (access_addr >= object_addr + cache->object_size) {
	220	rel_type = "to the right";
	221	rel_bytes = access_addr - (object_addr + cache->object_size);
	222	} else {
	223	rel_type = "inside";
	224	rel_bytes = access_addr - object_addr;
	225	}
	226
	227	pr_err("The buggy address is located %d bytes %s of\n"
	228	" %d-byte region [%p, %p)\n",
	229	rel_bytes, rel_type, cache->object_size, (void *)object_addr,
	230	(void *)(object_addr + cache->object_size));
	231	}
	232
	233	static void describe_object(struct kmem_cache cache, void object,
	234	const void *addr)
	235	{
	236	struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
	237
	238	if (cache->flags & SLAB_KASAN) {
	239	print_track(&alloc_info->alloc_track, "Allocated");
b1938599	240	pr_err("\n");
0c06f1f8	241	print_track(&alloc_info->free_track, "Freed");
b1938599	242	pr_err("\n");
0c06f1f8 AK	243	}
	244
	245	describe_object_addr(cache, object, addr);
7ed2f9e6	246	}
7ed2f9e6	247
5ab6d91a	248	static void print_address_description(void *addr)
0b24becc	249	{
db429f16	250	struct page *page = addr_to_page(addr);
b8c73fc2	251
db429f16	252	dump_stack();
b1938599	253	pr_err("\n");
db429f16 AK	254
	255	if (page && PageSlab(page)) {
	256	struct kmem_cache *cache = page->slab_cache;
0c06f1f8	257	void *object = nearest_obj(cache, page, addr);
db429f16	258
0c06f1f8	259	describe_object(cache, object, addr);
b8c73fc2 AR	260	}
b8c73fc2 AR	261
430a05f9 AK	262	if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) {
	263	pr_err("The buggy address belongs to the variable:\n");
	264	pr_err(" %pS\n", addr);
	265	}
	266
	267	if (page) {
	268	pr_err("The buggy address belongs to the page:\n");
	269	dump_page(page, "kasan: bad access detected");
bebf56a1	270	}
0b24becc AR	271	}
	272
	273	static bool row_is_guilty(const void row, const void guilty)
	274	{
	275	return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
	276	}
	277
	278	static int shadow_pointer_offset(const void row, const void shadow)
	279	{
	280	/* The length of ">ff00ff00ff00ff00: " is
	281	* 3 + (BITS_PER_LONG/8)*2 chars.
	282	*/
	283	return 3 + (BITS_PER_LONG/8)2 + (shadow - row)2 +
	284	(shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
	285	}
	286
	287	static void print_shadow_for_address(const void *addr)
	288	{
	289	int i;
	290	const void *shadow = kasan_mem_to_shadow(addr);
	291	const void *shadow_row;
	292
	293	shadow_row = (void *)round_down((unsigned long)shadow,
	294	SHADOW_BYTES_PER_ROW)
	295	- SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
	296
	297	pr_err("Memory state around the buggy address:\n");
	298
	299	for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
	300	const void *kaddr = kasan_shadow_to_mem(shadow_row);
	301	char buffer[4 + (BITS_PER_LONG/8)*2];
f2377d4e	302	char shadow_buf[SHADOW_BYTES_PER_ROW];
0b24becc AR	303
	304	snprintf(buffer, sizeof(buffer),
	305	(i == 0) ? ">%p: " : " %p: ", kaddr);
f2377d4e AK	306	/*
	307	* We should not pass a shadow pointer to generic
	308	* function, because generic functions may try to
	309	* access kasan mapping for the passed address.
	310	*/
f2377d4e	311	memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
0b24becc AR	312	print_hex_dump(KERN_ERR, buffer,
0b24becc AR	313	DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
f2377d4e	314	shadow_buf, SHADOW_BYTES_PER_ROW, 0);
0b24becc AR	315
	316	if (row_is_guilty(shadow_row, shadow))
	317	pr_err("%*c\n",
	318	shadow_pointer_offset(shadow_row, shadow),
	319	'^');
	320
	321	shadow_row += SHADOW_BYTES_PER_ROW;
	322	}
	323	}
	324
5ab6d91a AK	325	void kasan_report_double_free(struct kmem_cache cache, void object,
	326	void *ip)
	327	{
	328	unsigned long flags;
	329
	330	kasan_start_report(&flags);
	331	pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", ip);
b1938599	332	pr_err("\n");
5ab6d91a	333	print_address_description(object);
b1938599	334	pr_err("\n");
5ab6d91a AK	335	print_shadow_for_address(object);
	336	kasan_end_report(&flags);
	337	}
	338
e9121076	339	static void kasan_report_error(struct kasan_access_info *info)
0b24becc AR	340	{
	341	unsigned long flags;
	342
7e088978 AR	343	kasan_start_report(&flags);
7e088978 AR	344
7d418f7b	345	print_error_description(info);
b1938599	346	pr_err("\n");
7d418f7b	347
5e82cd12	348	if (!addr_has_shadow(info)) {
e9121076 AK	349	dump_stack();
e9121076 AK	350	} else {
5ab6d91a	351	print_address_description((void *)info->access_addr);
b1938599	352	pr_err("\n");
e9121076 AK	353	print_shadow_for_address(info->first_bad_addr);
e9121076 AK	354	}
7e088978 AR	355
7e088978 AR	356	kasan_end_report(&flags);
0b24becc AR	357	}
0b24becc AR	358
b0845ce5 MR	359	static unsigned long kasan_flags;
	360
	361	#define KASAN_BIT_REPORTED 0
	362	#define KASAN_BIT_MULTI_SHOT 1
	363
	364	bool kasan_save_enable_multi_shot(void)
	365	{
	366	return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
	367	}
	368	EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot);
	369
	370	void kasan_restore_multi_shot(bool enabled)
	371	{
	372	if (!enabled)
	373	clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
	374	}
	375	EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
	376
	377	static int __init kasan_set_multi_shot(char *str)
	378	{
	379	set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
	380	return 1;
	381	}
	382	__setup("kasan_multi_shot", kasan_set_multi_shot);
	383
	384	static inline bool kasan_report_enabled(void)
	385	{
	386	if (current->kasan_depth)
	387	return false;
	388	if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
	389	return true;
	390	return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
	391	}
	392
0b24becc AR	393	void kasan_report(unsigned long addr, size_t size,
	394	bool is_write, unsigned long ip)
	395	{
	396	struct kasan_access_info info;
	397
0ba8663c	398	if (likely(!kasan_report_enabled()))
0b24becc AR	399	return;
0b24becc AR	400
4f40c6e5 PZ	401	disable_trace_on_warning();
4f40c6e5 PZ	402
0b24becc	403	info.access_addr = (void *)addr;
e7701557	404	info.first_bad_addr = (void *)addr;
0b24becc AR	405	info.access_size = size;
	406	info.is_write = is_write;
	407	info.ip = ip;
e9121076	408
0b24becc AR	409	kasan_report_error(&info);
	410	}
	411
	412
	413	#define DEFINE_ASAN_REPORT_LOAD(size) \
	414	void __asan_report_load##size##_noabort(unsigned long addr) \
	415	{ \
	416	kasan_report(addr, size, false, _RET_IP_); \
	417	} \
	418	EXPORT_SYMBOL(__asan_report_load##size##_noabort)
	419
	420	#define DEFINE_ASAN_REPORT_STORE(size) \
	421	void __asan_report_store##size##_noabort(unsigned long addr) \
	422	{ \
	423	kasan_report(addr, size, true, _RET_IP_); \
	424	} \
	425	EXPORT_SYMBOL(__asan_report_store##size##_noabort)
	426
	427	DEFINE_ASAN_REPORT_LOAD(1);
	428	DEFINE_ASAN_REPORT_LOAD(2);
	429	DEFINE_ASAN_REPORT_LOAD(4);
	430	DEFINE_ASAN_REPORT_LOAD(8);
	431	DEFINE_ASAN_REPORT_LOAD(16);
	432	DEFINE_ASAN_REPORT_STORE(1);
	433	DEFINE_ASAN_REPORT_STORE(2);
	434	DEFINE_ASAN_REPORT_STORE(4);
	435	DEFINE_ASAN_REPORT_STORE(8);
	436	DEFINE_ASAN_REPORT_STORE(16);
	437
	438	void __asan_report_load_n_noabort(unsigned long addr, size_t size)
	439	{
	440	kasan_report(addr, size, false, _RET_IP_);
	441	}
	442	EXPORT_SYMBOL(__asan_report_load_n_noabort);
	443
	444	void __asan_report_store_n_noabort(unsigned long addr, size_t size)
	445	{
	446	kasan_report(addr, size, true, _RET_IP_);
	447	}
	448	EXPORT_SYMBOL(__asan_report_store_n_noabort);