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![Andrey Konovalov](/assets/img/avatar_default.png)
Use the new one. Link: http://lkml.kernel.org/r/de3b7ffc30a55178913a7d3865216aa7accf6c40.1515775666.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
451 lines
12 KiB
C
451 lines
12 KiB
C
/*
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* This file contains error reporting code.
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*
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* Copyright (c) 2014 Samsung Electronics Co., Ltd.
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* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
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*
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* Some code borrowed from https://github.com/xairy/kasan-prototype by
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* Andrey Konovalov <andreyknvl@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/bitops.h>
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#include <linux/ftrace.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/printk.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/stackdepot.h>
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#include <linux/stacktrace.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/kasan.h>
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#include <linux/module.h>
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#include <asm/sections.h>
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#include "kasan.h"
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#include "../slab.h"
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/* Shadow layout customization. */
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#define SHADOW_BYTES_PER_BLOCK 1
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#define SHADOW_BLOCKS_PER_ROW 16
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#define SHADOW_BYTES_PER_ROW (SHADOW_BLOCKS_PER_ROW * SHADOW_BYTES_PER_BLOCK)
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#define SHADOW_ROWS_AROUND_ADDR 2
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static const void *find_first_bad_addr(const void *addr, size_t size)
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{
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u8 shadow_val = *(u8 *)kasan_mem_to_shadow(addr);
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const void *first_bad_addr = addr;
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while (!shadow_val && first_bad_addr < addr + size) {
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first_bad_addr += KASAN_SHADOW_SCALE_SIZE;
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shadow_val = *(u8 *)kasan_mem_to_shadow(first_bad_addr);
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}
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return first_bad_addr;
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}
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static bool addr_has_shadow(struct kasan_access_info *info)
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{
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return (info->access_addr >=
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kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
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}
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static const char *get_shadow_bug_type(struct kasan_access_info *info)
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{
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const char *bug_type = "unknown-crash";
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u8 *shadow_addr;
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info->first_bad_addr = find_first_bad_addr(info->access_addr,
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info->access_size);
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shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
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/*
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* If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
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* at the next shadow byte to determine the type of the bad access.
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*/
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if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
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shadow_addr++;
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switch (*shadow_addr) {
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case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
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/*
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* In theory it's still possible to see these shadow values
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* due to a data race in the kernel code.
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*/
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bug_type = "out-of-bounds";
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break;
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case KASAN_PAGE_REDZONE:
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case KASAN_KMALLOC_REDZONE:
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bug_type = "slab-out-of-bounds";
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break;
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case KASAN_GLOBAL_REDZONE:
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bug_type = "global-out-of-bounds";
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break;
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case KASAN_STACK_LEFT:
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case KASAN_STACK_MID:
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case KASAN_STACK_RIGHT:
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case KASAN_STACK_PARTIAL:
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bug_type = "stack-out-of-bounds";
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break;
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case KASAN_FREE_PAGE:
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case KASAN_KMALLOC_FREE:
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bug_type = "use-after-free";
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break;
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case KASAN_USE_AFTER_SCOPE:
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bug_type = "use-after-scope";
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break;
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case KASAN_ALLOCA_LEFT:
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case KASAN_ALLOCA_RIGHT:
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bug_type = "alloca-out-of-bounds";
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break;
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}
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return bug_type;
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}
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static const char *get_wild_bug_type(struct kasan_access_info *info)
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{
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const char *bug_type = "unknown-crash";
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if ((unsigned long)info->access_addr < PAGE_SIZE)
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bug_type = "null-ptr-deref";
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else if ((unsigned long)info->access_addr < TASK_SIZE)
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bug_type = "user-memory-access";
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else
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bug_type = "wild-memory-access";
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return bug_type;
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}
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static const char *get_bug_type(struct kasan_access_info *info)
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{
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if (addr_has_shadow(info))
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return get_shadow_bug_type(info);
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return get_wild_bug_type(info);
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}
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static void print_error_description(struct kasan_access_info *info)
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{
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const char *bug_type = get_bug_type(info);
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pr_err("BUG: KASAN: %s in %pS\n",
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bug_type, (void *)info->ip);
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pr_err("%s of size %zu at addr %px by task %s/%d\n",
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info->is_write ? "Write" : "Read", info->access_size,
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info->access_addr, current->comm, task_pid_nr(current));
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}
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static inline bool kernel_or_module_addr(const void *addr)
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{
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if (addr >= (void *)_stext && addr < (void *)_end)
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return true;
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if (is_module_address((unsigned long)addr))
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return true;
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return false;
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}
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static inline bool init_task_stack_addr(const void *addr)
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{
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return addr >= (void *)&init_thread_union.stack &&
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(addr <= (void *)&init_thread_union.stack +
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sizeof(init_thread_union.stack));
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}
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static DEFINE_SPINLOCK(report_lock);
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static void kasan_start_report(unsigned long *flags)
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{
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/*
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* Make sure we don't end up in loop.
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*/
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kasan_disable_current();
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spin_lock_irqsave(&report_lock, *flags);
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pr_err("==================================================================\n");
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}
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static void kasan_end_report(unsigned long *flags)
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{
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pr_err("==================================================================\n");
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add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
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spin_unlock_irqrestore(&report_lock, *flags);
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if (panic_on_warn)
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panic("panic_on_warn set ...\n");
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kasan_enable_current();
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}
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static void print_track(struct kasan_track *track, const char *prefix)
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{
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pr_err("%s by task %u:\n", prefix, track->pid);
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if (track->stack) {
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struct stack_trace trace;
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depot_fetch_stack(track->stack, &trace);
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print_stack_trace(&trace, 0);
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} else {
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pr_err("(stack is not available)\n");
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}
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}
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static struct page *addr_to_page(const void *addr)
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{
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if ((addr >= (void *)PAGE_OFFSET) &&
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(addr < high_memory))
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return virt_to_head_page(addr);
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return NULL;
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}
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static void describe_object_addr(struct kmem_cache *cache, void *object,
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const void *addr)
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{
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unsigned long access_addr = (unsigned long)addr;
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unsigned long object_addr = (unsigned long)object;
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const char *rel_type;
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int rel_bytes;
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pr_err("The buggy address belongs to the object at %px\n"
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" which belongs to the cache %s of size %d\n",
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object, cache->name, cache->object_size);
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if (!addr)
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return;
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if (access_addr < object_addr) {
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rel_type = "to the left";
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rel_bytes = object_addr - access_addr;
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} else if (access_addr >= object_addr + cache->object_size) {
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rel_type = "to the right";
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rel_bytes = access_addr - (object_addr + cache->object_size);
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} else {
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rel_type = "inside";
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rel_bytes = access_addr - object_addr;
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}
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pr_err("The buggy address is located %d bytes %s of\n"
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" %d-byte region [%px, %px)\n",
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rel_bytes, rel_type, cache->object_size, (void *)object_addr,
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(void *)(object_addr + cache->object_size));
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}
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static void describe_object(struct kmem_cache *cache, void *object,
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const void *addr)
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{
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struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
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if (cache->flags & SLAB_KASAN) {
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print_track(&alloc_info->alloc_track, "Allocated");
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pr_err("\n");
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print_track(&alloc_info->free_track, "Freed");
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pr_err("\n");
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}
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describe_object_addr(cache, object, addr);
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}
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static void print_address_description(void *addr)
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{
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struct page *page = addr_to_page(addr);
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dump_stack();
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pr_err("\n");
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if (page && PageSlab(page)) {
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struct kmem_cache *cache = page->slab_cache;
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void *object = nearest_obj(cache, page, addr);
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describe_object(cache, object, addr);
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}
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if (kernel_or_module_addr(addr) && !init_task_stack_addr(addr)) {
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pr_err("The buggy address belongs to the variable:\n");
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pr_err(" %pS\n", addr);
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}
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if (page) {
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pr_err("The buggy address belongs to the page:\n");
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dump_page(page, "kasan: bad access detected");
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}
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}
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static bool row_is_guilty(const void *row, const void *guilty)
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{
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return (row <= guilty) && (guilty < row + SHADOW_BYTES_PER_ROW);
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}
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static int shadow_pointer_offset(const void *row, const void *shadow)
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{
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/* The length of ">ff00ff00ff00ff00: " is
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* 3 + (BITS_PER_LONG/8)*2 chars.
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*/
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return 3 + (BITS_PER_LONG/8)*2 + (shadow - row)*2 +
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(shadow - row) / SHADOW_BYTES_PER_BLOCK + 1;
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}
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static void print_shadow_for_address(const void *addr)
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{
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int i;
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const void *shadow = kasan_mem_to_shadow(addr);
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const void *shadow_row;
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shadow_row = (void *)round_down((unsigned long)shadow,
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SHADOW_BYTES_PER_ROW)
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- SHADOW_ROWS_AROUND_ADDR * SHADOW_BYTES_PER_ROW;
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pr_err("Memory state around the buggy address:\n");
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for (i = -SHADOW_ROWS_AROUND_ADDR; i <= SHADOW_ROWS_AROUND_ADDR; i++) {
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const void *kaddr = kasan_shadow_to_mem(shadow_row);
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char buffer[4 + (BITS_PER_LONG/8)*2];
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char shadow_buf[SHADOW_BYTES_PER_ROW];
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snprintf(buffer, sizeof(buffer),
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(i == 0) ? ">%px: " : " %px: ", kaddr);
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/*
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* We should not pass a shadow pointer to generic
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* function, because generic functions may try to
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* access kasan mapping for the passed address.
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*/
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memcpy(shadow_buf, shadow_row, SHADOW_BYTES_PER_ROW);
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print_hex_dump(KERN_ERR, buffer,
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DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
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shadow_buf, SHADOW_BYTES_PER_ROW, 0);
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if (row_is_guilty(shadow_row, shadow))
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pr_err("%*c\n",
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shadow_pointer_offset(shadow_row, shadow),
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'^');
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shadow_row += SHADOW_BYTES_PER_ROW;
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}
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}
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void kasan_report_invalid_free(void *object, unsigned long ip)
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{
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unsigned long flags;
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kasan_start_report(&flags);
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pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
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pr_err("\n");
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print_address_description(object);
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pr_err("\n");
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print_shadow_for_address(object);
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kasan_end_report(&flags);
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}
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static void kasan_report_error(struct kasan_access_info *info)
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{
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unsigned long flags;
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kasan_start_report(&flags);
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print_error_description(info);
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pr_err("\n");
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if (!addr_has_shadow(info)) {
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dump_stack();
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} else {
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print_address_description((void *)info->access_addr);
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pr_err("\n");
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print_shadow_for_address(info->first_bad_addr);
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}
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kasan_end_report(&flags);
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}
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static unsigned long kasan_flags;
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#define KASAN_BIT_REPORTED 0
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#define KASAN_BIT_MULTI_SHOT 1
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bool kasan_save_enable_multi_shot(void)
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{
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return test_and_set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
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}
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EXPORT_SYMBOL_GPL(kasan_save_enable_multi_shot);
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void kasan_restore_multi_shot(bool enabled)
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{
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if (!enabled)
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clear_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
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}
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EXPORT_SYMBOL_GPL(kasan_restore_multi_shot);
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static int __init kasan_set_multi_shot(char *str)
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{
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set_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags);
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return 1;
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}
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__setup("kasan_multi_shot", kasan_set_multi_shot);
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static inline bool kasan_report_enabled(void)
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{
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if (current->kasan_depth)
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return false;
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if (test_bit(KASAN_BIT_MULTI_SHOT, &kasan_flags))
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return true;
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return !test_and_set_bit(KASAN_BIT_REPORTED, &kasan_flags);
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}
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void kasan_report(unsigned long addr, size_t size,
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bool is_write, unsigned long ip)
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{
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struct kasan_access_info info;
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if (likely(!kasan_report_enabled()))
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return;
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disable_trace_on_warning();
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info.access_addr = (void *)addr;
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info.first_bad_addr = (void *)addr;
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info.access_size = size;
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info.is_write = is_write;
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info.ip = ip;
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kasan_report_error(&info);
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}
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#define DEFINE_ASAN_REPORT_LOAD(size) \
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void __asan_report_load##size##_noabort(unsigned long addr) \
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{ \
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kasan_report(addr, size, false, _RET_IP_); \
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} \
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EXPORT_SYMBOL(__asan_report_load##size##_noabort)
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#define DEFINE_ASAN_REPORT_STORE(size) \
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void __asan_report_store##size##_noabort(unsigned long addr) \
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{ \
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kasan_report(addr, size, true, _RET_IP_); \
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} \
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EXPORT_SYMBOL(__asan_report_store##size##_noabort)
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DEFINE_ASAN_REPORT_LOAD(1);
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DEFINE_ASAN_REPORT_LOAD(2);
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DEFINE_ASAN_REPORT_LOAD(4);
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DEFINE_ASAN_REPORT_LOAD(8);
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DEFINE_ASAN_REPORT_LOAD(16);
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DEFINE_ASAN_REPORT_STORE(1);
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DEFINE_ASAN_REPORT_STORE(2);
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DEFINE_ASAN_REPORT_STORE(4);
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DEFINE_ASAN_REPORT_STORE(8);
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DEFINE_ASAN_REPORT_STORE(16);
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void __asan_report_load_n_noabort(unsigned long addr, size_t size)
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{
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kasan_report(addr, size, false, _RET_IP_);
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}
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EXPORT_SYMBOL(__asan_report_load_n_noabort);
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void __asan_report_store_n_noabort(unsigned long addr, size_t size)
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{
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kasan_report(addr, size, true, _RET_IP_);
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}
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EXPORT_SYMBOL(__asan_report_store_n_noabort);
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