mm/kasan/report.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * This file contains common KASAN 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 <andreyknvl@gmail.com>
  */

 #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 <linux/sched/task_stack.h>
 #include <linux/uaccess.h>
 #include <trace/events/error_report.h>

 #include <asm/sections.h>

 #include <kunit/test.h>

 #include "kasan.h"
 #include "../slab.h"

 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 void print_error_description(struct kasan_access_info *info)
 {
 	pr_err("BUG: KASAN: %s in %pS\n",
 		kasan_get_bug_type(info), (void *)info->ip);
 	if (info->access_size)
 		pr_err("%s of size %zu at addr %px by task %s/%d\n",
 			info->is_write ? "Write" : "Read", info->access_size,
 			info->access_addr, current->comm, task_pid_nr(current));
 	else
 		pr_err("%s at addr %px by task %s/%d\n",
 			info->is_write ? "Write" : "Read",
 			info->access_addr, current->comm, task_pid_nr(current));
 }

 static DEFINE_SPINLOCK(report_lock);

 static void 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 end_report(unsigned long *flags, unsigned long addr)
 {
 	if (!kasan_async_mode_enabled())
 		trace_error_report_end(ERROR_DETECTOR_KASAN, addr);
 	pr_err("==================================================================\n");
 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 	spin_unlock_irqrestore(&report_lock, *flags);
 	if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) {
 		/*
 		 * This thread may hit another WARN() in the panic path.
 		 * Resetting this prevents additional WARN() from panicking the
 		 * system on this thread.  Other threads are blocked by the
 		 * panic_mutex in panic().
 		 */
 		panic_on_warn = 0;
 		panic("panic_on_warn set ...\n");
 	}
 #ifdef CONFIG_KASAN_HW_TAGS
 	if (kasan_flag_panic)
 		panic("kasan.fault=panic set ...\n");
 #endif
 	kasan_enable_current();
 }

 static void print_stack(depot_stack_handle_t stack)
 {
 	unsigned long *entries;
 	unsigned int nr_entries;

 	nr_entries = stack_depot_fetch(stack, &entries);
 	stack_trace_print(entries, nr_entries, 0);
 }

 static void print_track(struct kasan_track *track, const char *prefix)
 {
 	pr_err("%s by task %u:\n", prefix, track->pid);
 	if (track->stack) {
 		print_stack(track->stack);
 	} else {
 		pr_err("(stack is not available)\n");
 	}
 }

 struct page *kasan_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 %px\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 [%px, %px)\n",
 		rel_bytes, rel_type, cache->object_size, (void *)object_addr,
 		(void *)(object_addr + cache->object_size));
 }

 static void describe_object_stacks(struct kmem_cache *cache, void *object,
 					const void *addr, u8 tag)
 {
 	struct kasan_alloc_meta *alloc_meta;
 	struct kasan_track *free_track;

 	alloc_meta = kasan_get_alloc_meta(cache, object);
 	if (alloc_meta) {
 		print_track(&alloc_meta->alloc_track, "Allocated");
 		pr_err("\n");
 	}

 	free_track = kasan_get_free_track(cache, object, tag);
 	if (free_track) {
 		print_track(free_track, "Freed");
 		pr_err("\n");
 	}

 #ifdef CONFIG_KASAN_GENERIC
 	if (!alloc_meta)
 		return;
 	if (alloc_meta->aux_stack[0]) {
 		pr_err("Last potentially related work creation:\n");
 		print_stack(alloc_meta->aux_stack[0]);
 		pr_err("\n");
 	}
 	if (alloc_meta->aux_stack[1]) {
 		pr_err("Second to last potentially related work creation:\n");
 		print_stack(alloc_meta->aux_stack[1]);
 		pr_err("\n");
 	}
 #endif
 }

 static void describe_object(struct kmem_cache *cache, void *object,
 				const void *addr, u8 tag)
 {
 	if (kasan_stack_collection_enabled())
 		describe_object_stacks(cache, object, addr, tag);
 	describe_object_addr(cache, object, addr);
 }

 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(void *addr, u8 tag)
 {
 	struct page *page = kasan_addr_to_page(addr);

 	dump_stack_lvl(KERN_ERR);
 	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, tag);
 	}

 	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");
 	}

 	kasan_print_address_stack_frame(addr);
 }

 static bool meta_row_is_guilty(const void *row, const void *addr)
 {
 	return (row <= addr) && (addr < row + META_MEM_BYTES_PER_ROW);
 }

 static int meta_pointer_offset(const void *row, const void *addr)
 {
 	/*
 	 * Memory state around the buggy address:
 	 *  ff00ff00ff00ff00: 00 00 00 05 fe fe fe fe fe fe fe fe fe fe fe fe
 	 *  ...
 	 *
 	 * The length of ">ff00ff00ff00ff00: " is
 	 *    3 + (BITS_PER_LONG / 8) * 2 chars.
 	 * The length of each granule metadata is 2 bytes
 	 *    plus 1 byte for space.
 	 */
 	return 3 + (BITS_PER_LONG / 8) * 2 +
 		(addr - row) / KASAN_GRANULE_SIZE * 3 + 1;
 }

 static void print_memory_metadata(const void *addr)
 {
 	int i;
 	void *row;

 	row = (void *)round_down((unsigned long)addr, META_MEM_BYTES_PER_ROW)
 			- META_ROWS_AROUND_ADDR * META_MEM_BYTES_PER_ROW;

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

 	for (i = -META_ROWS_AROUND_ADDR; i <= META_ROWS_AROUND_ADDR; i++) {
 		char buffer[4 + (BITS_PER_LONG / 8) * 2];
 		char metadata[META_BYTES_PER_ROW];

 		snprintf(buffer, sizeof(buffer),
 				(i == 0) ? ">%px: " : " %px: ", row);

 		/*
 		 * We should not pass a shadow pointer to generic
 		 * function, because generic functions may try to
 		 * access kasan mapping for the passed address.
 		 */
 		kasan_metadata_fetch_row(&metadata[0], row);

 		print_hex_dump(KERN_ERR, buffer,
 			DUMP_PREFIX_NONE, META_BYTES_PER_ROW, 1,
 			metadata, META_BYTES_PER_ROW, 0);

 		if (meta_row_is_guilty(row, addr))
 			pr_err("%*c\n", meta_pointer_offset(row, addr), '^');

 		row += META_MEM_BYTES_PER_ROW;
 	}
 }

 static bool report_enabled(void)
 {
 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 	if (current->kasan_depth)
 		return false;
 #endif
 	if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
 		return true;
 	return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
 }

 #if IS_ENABLED(CONFIG_KUNIT)
 static void kasan_update_kunit_status(struct kunit *cur_test)
 {
 	struct kunit_resource *resource;
 	struct kunit_kasan_expectation *kasan_data;

 	resource = kunit_find_named_resource(cur_test, "kasan_data");

 	if (!resource) {
 		kunit_set_failure(cur_test);
 		return;
 	}

 	kasan_data = (struct kunit_kasan_expectation *)resource->data;
 	WRITE_ONCE(kasan_data->report_found, true);
 	kunit_put_resource(resource);
 }
 #endif /* IS_ENABLED(CONFIG_KUNIT) */

 void kasan_report_invalid_free(void *object, unsigned long ip)
 {
 	unsigned long flags;
 	u8 tag = get_tag(object);

 	object = kasan_reset_tag(object);

 #if IS_ENABLED(CONFIG_KUNIT)
 	if (current->kunit_test)
 		kasan_update_kunit_status(current->kunit_test);
 #endif /* IS_ENABLED(CONFIG_KUNIT) */

 	start_report(&flags);
 	pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
 	kasan_print_tags(tag, object);
 	pr_err("\n");
 	print_address_description(object, tag);
 	pr_err("\n");
 	print_memory_metadata(object);
 	end_report(&flags, (unsigned long)object);
 }

 #ifdef CONFIG_KASAN_HW_TAGS
 void kasan_report_async(void)
 {
 	unsigned long flags;

 #if IS_ENABLED(CONFIG_KUNIT)
 	if (current->kunit_test)
 		kasan_update_kunit_status(current->kunit_test);
 #endif /* IS_ENABLED(CONFIG_KUNIT) */

 	start_report(&flags);
 	pr_err("BUG: KASAN: invalid-access\n");
 	pr_err("Asynchronous mode enabled: no access details available\n");
 	pr_err("\n");
 	dump_stack_lvl(KERN_ERR);
 	end_report(&flags, 0);
 }
 #endif /* CONFIG_KASAN_HW_TAGS */

 static void __kasan_report(unsigned long addr, size_t size, bool is_write,
 				unsigned long ip)
 {
 	struct kasan_access_info info;
 	void *tagged_addr;
 	void *untagged_addr;
 	unsigned long flags;

 #if IS_ENABLED(CONFIG_KUNIT)
 	if (current->kunit_test)
 		kasan_update_kunit_status(current->kunit_test);
 #endif /* IS_ENABLED(CONFIG_KUNIT) */

 	disable_trace_on_warning();

 	tagged_addr = (void *)addr;
 	untagged_addr = kasan_reset_tag(tagged_addr);

 	info.access_addr = tagged_addr;
 	if (addr_has_metadata(untagged_addr))
 		info.first_bad_addr =
 			kasan_find_first_bad_addr(tagged_addr, size);
 	else
 		info.first_bad_addr = untagged_addr;
 	info.access_size = size;
 	info.is_write = is_write;
 	info.ip = ip;

 	start_report(&flags);

 	print_error_description(&info);
 	if (addr_has_metadata(untagged_addr))
 		kasan_print_tags(get_tag(tagged_addr), info.first_bad_addr);
 	pr_err("\n");

 	if (addr_has_metadata(untagged_addr)) {
 		print_address_description(untagged_addr, get_tag(tagged_addr));
 		pr_err("\n");
 		print_memory_metadata(info.first_bad_addr);
 	} else {
 		dump_stack_lvl(KERN_ERR);
 	}

 	end_report(&flags, addr);
 }

 bool kasan_report(unsigned long addr, size_t size, bool is_write,
 			unsigned long ip)
 {
 	unsigned long flags = user_access_save();
 	bool ret = false;

 	if (likely(report_enabled())) {
 		__kasan_report(addr, size, is_write, ip);
 		ret = true;
 	}

 	user_access_restore(flags);

 	return ret;
 }

 #ifdef CONFIG_KASAN_INLINE
 /*
  * With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
  * canonical half of the address space) cause out-of-bounds shadow memory reads
  * before the actual access. For addresses in the low canonical half of the
  * address space, as well as most non-canonical addresses, that out-of-bounds
  * shadow memory access lands in the non-canonical part of the address space.
  * Help the user figure out what the original bogus pointer was.
  */
 void kasan_non_canonical_hook(unsigned long addr)
 {
 	unsigned long orig_addr;
 	const char *bug_type;

 	if (addr < KASAN_SHADOW_OFFSET)
 		return;

 	orig_addr = (addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT;
 	/*
 	 * For faults near the shadow address for NULL, we can be fairly certain
 	 * that this is a KASAN shadow memory access.
 	 * For faults that correspond to shadow for low canonical addresses, we
 	 * can still be pretty sure - that shadow region is a fairly narrow
 	 * chunk of the non-canonical address space.
 	 * But faults that look like shadow for non-canonical addresses are a
 	 * really large chunk of the address space. In that case, we still
 	 * print the decoded address, but make it clear that this is not
 	 * necessarily what's actually going on.
 	 */
 	if (orig_addr < PAGE_SIZE)
 		bug_type = "null-ptr-deref";
 	else if (orig_addr < TASK_SIZE)
 		bug_type = "probably user-memory-access";
 	else
 		bug_type = "maybe wild-memory-access";
 	pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type,
 		 orig_addr, orig_addr + KASAN_GRANULE_SIZE - 1);
 }
 #endif
	// SPDX-License-Identifier: GPL-2.0
	/*
	* This file contains common KASAN 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 <andreyknvl@gmail.com>
	*/

	#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 <linux/sched/task_stack.h>
	#include <linux/uaccess.h>
	#include <trace/events/error_report.h>

	#include <asm/sections.h>

	#include <kunit/test.h>

	#include "kasan.h"
	#include "../slab.h"

	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 void print_error_description(struct kasan_access_info *info)
	{
	pr_err("BUG: KASAN: %s in %pS\n",
	kasan_get_bug_type(info), (void *)info->ip);
	if (info->access_size)
	pr_err("%s of size %zu at addr %px by task %s/%d\n",
	info->is_write ? "Write" : "Read", info->access_size,
	info->access_addr, current->comm, task_pid_nr(current));
	else
	pr_err("%s at addr %px by task %s/%d\n",
	info->is_write ? "Write" : "Read",
	info->access_addr, current->comm, task_pid_nr(current));
	}

	static DEFINE_SPINLOCK(report_lock);

	static void 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 end_report(unsigned long *flags, unsigned long addr)
	{
	if (!kasan_async_mode_enabled())
	trace_error_report_end(ERROR_DETECTOR_KASAN, addr);
	pr_err("==================================================================\n");
	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
	spin_unlock_irqrestore(&report_lock, *flags);
	if (panic_on_warn && !test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags)) {
	/*
	* This thread may hit another WARN() in the panic path.
	* Resetting this prevents additional WARN() from panicking the
	* system on this thread. Other threads are blocked by the
	* panic_mutex in panic().
	*/
	panic_on_warn = 0;
	panic("panic_on_warn set ...\n");
	}
	#ifdef CONFIG_KASAN_HW_TAGS
	if (kasan_flag_panic)
	panic("kasan.fault=panic set ...\n");
	#endif
	kasan_enable_current();
	}

	static void print_stack(depot_stack_handle_t stack)
	{
	unsigned long *entries;
	unsigned int nr_entries;

	nr_entries = stack_depot_fetch(stack, &entries);
	stack_trace_print(entries, nr_entries, 0);
	}

	static void print_track(struct kasan_track track, const char prefix)
	{
	pr_err("%s by task %u:\n", prefix, track->pid);
	if (track->stack) {
	print_stack(track->stack);
	} else {
	pr_err("(stack is not available)\n");
	}
	}

	struct page kasan_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 %px\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 [%px, %px)\n",
	rel_bytes, rel_type, cache->object_size, (void *)object_addr,
	(void *)(object_addr + cache->object_size));
	}

	static void describe_object_stacks(struct kmem_cache cache, void object,
	const void *addr, u8 tag)
	{
	struct kasan_alloc_meta *alloc_meta;
	struct kasan_track *free_track;

	alloc_meta = kasan_get_alloc_meta(cache, object);
	if (alloc_meta) {
	print_track(&alloc_meta->alloc_track, "Allocated");
	pr_err("\n");
	}

	free_track = kasan_get_free_track(cache, object, tag);
	if (free_track) {
	print_track(free_track, "Freed");
	pr_err("\n");
	}

	#ifdef CONFIG_KASAN_GENERIC
	if (!alloc_meta)
	return;
	if (alloc_meta->aux_stack[0]) {
	pr_err("Last potentially related work creation:\n");
	print_stack(alloc_meta->aux_stack[0]);
	pr_err("\n");
	}
	if (alloc_meta->aux_stack[1]) {
	pr_err("Second to last potentially related work creation:\n");
	print_stack(alloc_meta->aux_stack[1]);
	pr_err("\n");
	}
	#endif
	}

	static void describe_object(struct kmem_cache cache, void object,
	const void *addr, u8 tag)
	{
	if (kasan_stack_collection_enabled())
	describe_object_stacks(cache, object, addr, tag);
	describe_object_addr(cache, object, addr);
	}

	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(void *addr, u8 tag)
	{
	struct page *page = kasan_addr_to_page(addr);

	dump_stack_lvl(KERN_ERR);
	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, tag);
	}

	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");
	}

	kasan_print_address_stack_frame(addr);
	}

	static bool meta_row_is_guilty(const void row, const void addr)
	{
	return (row <= addr) && (addr < row + META_MEM_BYTES_PER_ROW);
	}

	static int meta_pointer_offset(const void row, const void addr)
	{
	/*
	* Memory state around the buggy address:
	* ff00ff00ff00ff00: 00 00 00 05 fe fe fe fe fe fe fe fe fe fe fe fe
	* ...
	*
	* The length of ">ff00ff00ff00ff00: " is
	* 3 + (BITS_PER_LONG / 8) * 2 chars.
	* The length of each granule metadata is 2 bytes
	* plus 1 byte for space.
	*/
	return 3 + (BITS_PER_LONG / 8) * 2 +
	(addr - row) / KASAN_GRANULE_SIZE * 3 + 1;
	}

	static void print_memory_metadata(const void *addr)
	{
	int i;
	void *row;

	row = (void *)round_down((unsigned long)addr, META_MEM_BYTES_PER_ROW)
	- META_ROWS_AROUND_ADDR * META_MEM_BYTES_PER_ROW;

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

	for (i = -META_ROWS_AROUND_ADDR; i <= META_ROWS_AROUND_ADDR; i++) {
	char buffer[4 + (BITS_PER_LONG / 8) * 2];
	char metadata[META_BYTES_PER_ROW];

	snprintf(buffer, sizeof(buffer),
	(i == 0) ? ">%px: " : " %px: ", row);

	/*
	* We should not pass a shadow pointer to generic
	* function, because generic functions may try to
	* access kasan mapping for the passed address.
	*/
	kasan_metadata_fetch_row(&metadata[0], row);

	print_hex_dump(KERN_ERR, buffer,
	DUMP_PREFIX_NONE, META_BYTES_PER_ROW, 1,
	metadata, META_BYTES_PER_ROW, 0);

	if (meta_row_is_guilty(row, addr))
	pr_err("%*c\n", meta_pointer_offset(row, addr), '^');

	row += META_MEM_BYTES_PER_ROW;
	}
	}

	static bool report_enabled(void)
	{
	#if defined(CONFIG_KASAN_GENERIC) \|\| defined(CONFIG_KASAN_SW_TAGS)
	if (current->kasan_depth)
	return false;
	#endif
	if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
	return true;
	return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
	}

	#if IS_ENABLED(CONFIG_KUNIT)
	static void kasan_update_kunit_status(struct kunit *cur_test)
	{
	struct kunit_resource *resource;
	struct kunit_kasan_expectation *kasan_data;

	resource = kunit_find_named_resource(cur_test, "kasan_data");

	if (!resource) {
	kunit_set_failure(cur_test);
	return;
	}

	kasan_data = (struct kunit_kasan_expectation *)resource->data;
	WRITE_ONCE(kasan_data->report_found, true);
	kunit_put_resource(resource);
	}
	#endif /* IS_ENABLED(CONFIG_KUNIT) */

	void kasan_report_invalid_free(void *object, unsigned long ip)
	{
	unsigned long flags;
	u8 tag = get_tag(object);

	object = kasan_reset_tag(object);

	#if IS_ENABLED(CONFIG_KUNIT)
	if (current->kunit_test)
	kasan_update_kunit_status(current->kunit_test);
	#endif /* IS_ENABLED(CONFIG_KUNIT) */

	start_report(&flags);
	pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
	kasan_print_tags(tag, object);
	pr_err("\n");
	print_address_description(object, tag);
	pr_err("\n");
	print_memory_metadata(object);
	end_report(&flags, (unsigned long)object);
	}

	#ifdef CONFIG_KASAN_HW_TAGS
	void kasan_report_async(void)
	{
	unsigned long flags;

	#if IS_ENABLED(CONFIG_KUNIT)
	if (current->kunit_test)
	kasan_update_kunit_status(current->kunit_test);
	#endif /* IS_ENABLED(CONFIG_KUNIT) */

	start_report(&flags);
	pr_err("BUG: KASAN: invalid-access\n");
	pr_err("Asynchronous mode enabled: no access details available\n");
	pr_err("\n");
	dump_stack_lvl(KERN_ERR);
	end_report(&flags, 0);
	}
	#endif /* CONFIG_KASAN_HW_TAGS */

	static void __kasan_report(unsigned long addr, size_t size, bool is_write,
	unsigned long ip)
	{
	struct kasan_access_info info;
	void *tagged_addr;
	void *untagged_addr;
	unsigned long flags;

	#if IS_ENABLED(CONFIG_KUNIT)
	if (current->kunit_test)
	kasan_update_kunit_status(current->kunit_test);
	#endif /* IS_ENABLED(CONFIG_KUNIT) */

	disable_trace_on_warning();

	tagged_addr = (void *)addr;
	untagged_addr = kasan_reset_tag(tagged_addr);

	info.access_addr = tagged_addr;
	if (addr_has_metadata(untagged_addr))
	info.first_bad_addr =
	kasan_find_first_bad_addr(tagged_addr, size);
	else
	info.first_bad_addr = untagged_addr;
	info.access_size = size;
	info.is_write = is_write;
	info.ip = ip;

	start_report(&flags);

	print_error_description(&info);
	if (addr_has_metadata(untagged_addr))
	kasan_print_tags(get_tag(tagged_addr), info.first_bad_addr);
	pr_err("\n");

	if (addr_has_metadata(untagged_addr)) {
	print_address_description(untagged_addr, get_tag(tagged_addr));
	pr_err("\n");
	print_memory_metadata(info.first_bad_addr);
	} else {
	dump_stack_lvl(KERN_ERR);
	}

	end_report(&flags, addr);
	}

	bool kasan_report(unsigned long addr, size_t size, bool is_write,
	unsigned long ip)
	{
	unsigned long flags = user_access_save();
	bool ret = false;

	if (likely(report_enabled())) {
	__kasan_report(addr, size, is_write, ip);
	ret = true;
	}

	user_access_restore(flags);

	return ret;
	}

	#ifdef CONFIG_KASAN_INLINE
	/*
	* With CONFIG_KASAN_INLINE, accesses to bogus pointers (outside the high
	* canonical half of the address space) cause out-of-bounds shadow memory reads
	* before the actual access. For addresses in the low canonical half of the
	* address space, as well as most non-canonical addresses, that out-of-bounds
	* shadow memory access lands in the non-canonical part of the address space.
	* Help the user figure out what the original bogus pointer was.
	*/
	void kasan_non_canonical_hook(unsigned long addr)
	{
	unsigned long orig_addr;
	const char *bug_type;

	if (addr < KASAN_SHADOW_OFFSET)
	return;

	orig_addr = (addr - KASAN_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT;
	/*
	* For faults near the shadow address for NULL, we can be fairly certain
	* that this is a KASAN shadow memory access.
	* For faults that correspond to shadow for low canonical addresses, we
	* can still be pretty sure - that shadow region is a fairly narrow
	* chunk of the non-canonical address space.
	* But faults that look like shadow for non-canonical addresses are a
	* really large chunk of the address space. In that case, we still
	* print the decoded address, but make it clear that this is not
	* necessarily what's actually going on.
	*/
	if (orig_addr < PAGE_SIZE)
	bug_type = "null-ptr-deref";
	else if (orig_addr < TASK_SIZE)
	bug_type = "probably user-memory-access";
	else
	bug_type = "maybe wild-memory-access";
	pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type,
	orig_addr, orig_addr + KASAN_GRANULE_SIZE - 1);
	}
	#endif