[linux.git] / mm / kasan / report.c

/*
 * This file contains error reporting code.
 *
 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
 * Author: Andrey Ryabinin <[email protected]>
 *
 * Some of code borrowed from https://github.com/xairy/linux by
 *        Andrey Konovalov <[email protected]>
 *
 * 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_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 KASAN_GLOBAL_REDZONE:
	case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
		bug_type = "out of bounds access";
		break;
	case KASAN_STACK_LEFT:
	case KASAN_STACK_MID:
	case KASAN_STACK_RIGHT:
	case KASAN_STACK_PARTIAL:
		bug_type = "out of bounds on stack";
		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");
	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 <[email protected]>
0b24becc AR	6	*
	7	* Some of code borrowed from https://github.com/xairy/linux by
	8	* Andrey Konovalov <[email protected]>
	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	{
	52	const char *bug_type = "unknown crash";
	53	u8 shadow_val;
	54
	55	info->first_bad_addr = find_first_bad_addr(info->access_addr,
	56	info->access_size);
	57
	58	shadow_val = (u8 )kasan_mem_to_shadow(info->first_bad_addr);
	59
	60	switch (shadow_val) {
b8c73fc2	61	case KASAN_FREE_PAGE:
0316bec2	62	case KASAN_KMALLOC_FREE:
b8c73fc2 AR	63	bug_type = "use after free";
b8c73fc2 AR	64	break;
0316bec2 AR	65	case KASAN_PAGE_REDZONE:
0316bec2 AR	66	case KASAN_KMALLOC_REDZONE:
bebf56a1	67	case KASAN_GLOBAL_REDZONE:
0b24becc AR	68	case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
	69	bug_type = "out of bounds access";
	70	break;
c420f167 AR	71	case KASAN_STACK_LEFT:
	72	case KASAN_STACK_MID:
	73	case KASAN_STACK_RIGHT:
	74	case KASAN_STACK_PARTIAL:
	75	bug_type = "out of bounds on stack";
	76	break;
0b24becc AR	77	}
	78
	79	pr_err("BUG: KASan: %s in %pS at addr %p\n",
	80	bug_type, (void *)info->ip,
	81	info->access_addr);
	82	pr_err("%s of size %zu by task %s/%d\n",
	83	info->is_write ? "Write" : "Read",
	84	info->access_size, current->comm, task_pid_nr(current));
	85	}
	86
bebf56a1 AR	87	static inline bool kernel_or_module_addr(const void *addr)
bebf56a1 AR	88	{
527f215b AK	89	if (addr >= (void )_stext && addr < (void )_end)
	90	return true;
	91	if (is_module_address((unsigned long)addr))
	92	return true;
	93	return false;
bebf56a1 AR	94	}
	95
	96	static inline bool init_task_stack_addr(const void *addr)
	97	{
	98	return addr >= (void *)&init_thread_union.stack &&
	99	(addr <= (void *)&init_thread_union.stack +
	100	sizeof(init_thread_union.stack));
	101	}
	102
0b24becc AR	103	static void print_address_description(struct kasan_access_info *info)
0b24becc AR	104	{
b8c73fc2 AR	105	const void *addr = info->access_addr;
	106
	107	if ((addr >= (void *)PAGE_OFFSET) &&
	108	(addr < high_memory)) {
	109	struct page *page = virt_to_head_page(addr);
0316bec2 AR	110
	111	if (PageSlab(page)) {
	112	void *object;
	113	struct kmem_cache *cache = page->slab_cache;
	114	void *last_object;
	115
	116	object = virt_to_obj(cache, page_address(page), addr);
	117	last_object = page_address(page) +
	118	page->objects * cache->size;
	119
	120	if (unlikely(object > last_object))
	121	object = last_object; /* we hit into padding */
	122
	123	object_err(cache, page, object,
	124	"kasan: bad access detected");
	125	return;
	126	}
b8c73fc2 AR	127	dump_page(page, "kasan: bad access detected");
	128	}
	129
bebf56a1 AR	130	if (kernel_or_module_addr(addr)) {
	131	if (!init_task_stack_addr(addr))
	132	pr_err("Address belongs to variable %pS\n", addr);
	133	}
	134
0b24becc AR	135	dump_stack();
	136	}
	137
	138	static bool row_is_guilty(const void row, const void guilty)
	139	{
	140	return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
	141	}
	142
	143	static int shadow_pointer_offset(const void row, const void shadow)
	144	{
	145	/* The length of ">ff00ff00ff00ff00: " is
	146	* 3 + (BITS_PER_LONG/8)*2 chars.
	147	*/
	148	return 3 + (BITS_PER_LONG/8)2 + (shadow - row)2 +
	149	(shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
	150	}
	151
	152	static void print_shadow_for_address(const void *addr)
	153	{
	154	int i;
	155	const void *shadow = kasan_mem_to_shadow(addr);
	156	const void *shadow_row;
	157
	158	shadow_row = (void *)round_down((unsigned long)shadow,
	159	SHADOW_BYTES_PER_ROW)
	160	- SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
	161
	162	pr_err("Memory state around the buggy address:\n");
	163
	164	for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
	165	const void *kaddr = kasan_shadow_to_mem(shadow_row);
	166	char buffer[4 + (BITS_PER_LONG/8)*2];
f2377d4e	167	char shadow_buf[SHADOW_BYTES_PER_ROW];
0b24becc AR	168
	169	snprintf(buffer, sizeof(buffer),
	170	(i == 0) ? ">%p: " : " %p: ", kaddr);
f2377d4e AK	171	/*
	172	* We should not pass a shadow pointer to generic
	173	* function, because generic functions may try to
	174	* access kasan mapping for the passed address.
	175	*/
f2377d4e	176	memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
0b24becc AR	177	print_hex_dump(KERN_ERR, buffer,
0b24becc AR	178	DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
f2377d4e	179	shadow_buf, SHADOW_BYTES_PER_ROW, 0);
0b24becc AR	180
	181	if (row_is_guilty(shadow_row, shadow))
	182	pr_err("%*c\n",
	183	shadow_pointer_offset(shadow_row, shadow),
	184	'^');
	185
	186	shadow_row += SHADOW_BYTES_PER_ROW;
	187	}
	188	}
	189
	190	static DEFINE_SPINLOCK(report_lock);
	191
e9121076	192	static void kasan_report_error(struct kasan_access_info *info)
0b24becc AR	193	{
0b24becc AR	194	unsigned long flags;
e9121076	195	const char *bug_type;
0b24becc	196
fc5aeeaf AK	197	/*
	198	* Make sure we don't end up in loop.
	199	*/
	200	kasan_disable_current();
0b24becc AR	201	spin_lock_irqsave(&report_lock, flags);
	202	pr_err("================================="
	203	"=================================\n");
e9121076 AK	204	if (info->access_addr <
	205	kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
	206	if ((unsigned long)info->access_addr < PAGE_SIZE)
	207	bug_type = "null-ptr-deref";
	208	else if ((unsigned long)info->access_addr < TASK_SIZE)
	209	bug_type = "user-memory-access";
	210	else
	211	bug_type = "wild-memory-access";
	212	pr_err("BUG: KASan: %s on address %p\n",
	213	bug_type, info->access_addr);
	214	pr_err("%s of size %zu by task %s/%d\n",
	215	info->is_write ? "Write" : "Read",
	216	info->access_size, current->comm,
	217	task_pid_nr(current));
	218	dump_stack();
	219	} else {
	220	print_error_description(info);
	221	print_address_description(info);
	222	print_shadow_for_address(info->first_bad_addr);
	223	}
0b24becc AR	224	pr_err("================================="
	225	"=================================\n");
	226	spin_unlock_irqrestore(&report_lock, flags);
fc5aeeaf	227	kasan_enable_current();
0b24becc AR	228	}
	229
	230	void kasan_report(unsigned long addr, size_t size,
	231	bool is_write, unsigned long ip)
	232	{
	233	struct kasan_access_info info;
	234
0ba8663c	235	if (likely(!kasan_report_enabled()))
0b24becc AR	236	return;
	237
	238	info.access_addr = (void *)addr;
	239	info.access_size = size;
	240	info.is_write = is_write;
	241	info.ip = ip;
e9121076	242
0b24becc AR	243	kasan_report_error(&info);
	244	}
	245
	246
	247	#define DEFINE_ASAN_REPORT_LOAD(size) \
	248	void __asan_report_load##size##_noabort(unsigned long addr) \
	249	{ \
	250	kasan_report(addr, size, false, _RET_IP_); \
	251	} \
	252	EXPORT_SYMBOL(__asan_report_load##size##_noabort)
	253
	254	#define DEFINE_ASAN_REPORT_STORE(size) \
	255	void __asan_report_store##size##_noabort(unsigned long addr) \
	256	{ \
	257	kasan_report(addr, size, true, _RET_IP_); \
	258	} \
	259	EXPORT_SYMBOL(__asan_report_store##size##_noabort)
	260
	261	DEFINE_ASAN_REPORT_LOAD(1);
	262	DEFINE_ASAN_REPORT_LOAD(2);
	263	DEFINE_ASAN_REPORT_LOAD(4);
	264	DEFINE_ASAN_REPORT_LOAD(8);
	265	DEFINE_ASAN_REPORT_LOAD(16);
	266	DEFINE_ASAN_REPORT_STORE(1);
	267	DEFINE_ASAN_REPORT_STORE(2);
	268	DEFINE_ASAN_REPORT_STORE(4);
	269	DEFINE_ASAN_REPORT_STORE(8);
	270	DEFINE_ASAN_REPORT_STORE(16);
	271
	272	void __asan_report_load_n_noabort(unsigned long addr, size_t size)
	273	{
	274	kasan_report(addr, size, false, _RET_IP_);
	275	}
	276	EXPORT_SYMBOL(__asan_report_load_n_noabort);
	277
	278	void __asan_report_store_n_noabort(unsigned long addr, size_t size)
	279	{
	280	kasan_report(addr, size, true, _RET_IP_);
	281	}
	282	EXPORT_SYMBOL(__asan_report_store_n_noabort);