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

 // SPDX-License-Identifier: GPL-2.0
 /*
  * This file contains common generic and tag-based 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>
  *
  * 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 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",
 		get_bug_type(info), (void *)info->ip);
 	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));
 }

 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)
 {
 	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 %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(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 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)
 {
 	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) ? ">%px: " : " %px: ", 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 bool 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_invalid_free(void *object, unsigned long ip)
 {
 	unsigned long flags;

 	start_report(&flags);
 	pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
 	print_tags(get_tag(object), reset_tag(object));
 	object = reset_tag(object);
 	pr_err("\n");
 	print_address_description(object);
 	pr_err("\n");
 	print_shadow_for_address(object);
 	end_report(&flags);
 }

 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 (likely(!report_enabled()))
 		return;

 	disable_trace_on_warning();

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

 	info.access_addr = tagged_addr;
 	if (addr_has_shadow(untagged_addr))
 		info.first_bad_addr = 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_shadow(untagged_addr))
 		print_tags(get_tag(tagged_addr), info.first_bad_addr);
 	pr_err("\n");

 	if (addr_has_shadow(untagged_addr)) {
 		print_address_description(untagged_addr);
 		pr_err("\n");
 		print_shadow_for_address(info.first_bad_addr);
 	} else {
 		dump_stack();
 	}

 	end_report(&flags);
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* This file contains common generic and tag-based 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>
	*
	* 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 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",
	get_bug_type(info), (void *)info->ip);
	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));
	}

	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)
	{
	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 %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(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 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)
	{
	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) ? ">%px: " : " %px: ", 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 bool 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_invalid_free(void *object, unsigned long ip)
	{
	unsigned long flags;

	start_report(&flags);
	pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
	print_tags(get_tag(object), reset_tag(object));
	object = reset_tag(object);
	pr_err("\n");
	print_address_description(object);
	pr_err("\n");
	print_shadow_for_address(object);
	end_report(&flags);
	}

	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 (likely(!report_enabled()))
	return;

	disable_trace_on_warning();

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

	info.access_addr = tagged_addr;
	if (addr_has_shadow(untagged_addr))
	info.first_bad_addr = 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_shadow(untagged_addr))
	print_tags(get_tag(tagged_addr), info.first_bad_addr);
	pr_err("\n");

	if (addr_has_shadow(untagged_addr)) {
	print_address_description(untagged_addr);
	pr_err("\n");
	print_shadow_for_address(info.first_bad_addr);
	} else {
	dump_stack();
	}

	end_report(&flags);
	}