![Andrey Ryabinin](/assets/img/avatar_default.png)
Use after scope bugs detector seems to be almost entirely useless for the linux kernel. It exists over two years, but I've seen only one valid bug so far [1]. And the bug was fixed before it has been reported. There were some other use-after-scope reports, but they were false-positives due to different reasons like incompatibility with structleak plugin. This feature significantly increases stack usage, especially with GCC < 9 version, and causes a 32K stack overflow. It probably adds performance penalty too. Given all that, let's remove use-after-scope detector entirely. While preparing this patch I've noticed that we mistakenly enable use-after-scope detection for clang compiler regardless of CONFIG_KASAN_EXTRA setting. This is also fixed now. [1] http://lkml.kernel.org/r/<20171129052106.rhgbjhhis53hkgfn@wfg-t540p.sh.intel.com> Link: http://lkml.kernel.org/r/20190111185842.13978-1-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Will Deacon <will.deacon@arm.com> [arm64] Cc: Qian Cai <cai@lca.pw> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
151 lines
4 KiB
C
151 lines
4 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* This file contains generic KASAN specific 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"
|
|
|
|
void *find_first_bad_addr(void *addr, size_t size)
|
|
{
|
|
void *p = addr;
|
|
|
|
while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
|
|
p += KASAN_SHADOW_SCALE_SIZE;
|
|
return p;
|
|
}
|
|
|
|
static const char *get_shadow_bug_type(struct kasan_access_info *info)
|
|
{
|
|
const char *bug_type = "unknown-crash";
|
|
u8 *shadow_addr;
|
|
|
|
shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);
|
|
|
|
/*
|
|
* If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
|
|
* at the next shadow byte to determine the type of the bad access.
|
|
*/
|
|
if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
|
|
shadow_addr++;
|
|
|
|
switch (*shadow_addr) {
|
|
case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
|
|
/*
|
|
* In theory it's still possible to see these shadow values
|
|
* due to a data race in the kernel code.
|
|
*/
|
|
bug_type = "out-of-bounds";
|
|
break;
|
|
case KASAN_PAGE_REDZONE:
|
|
case KASAN_KMALLOC_REDZONE:
|
|
bug_type = "slab-out-of-bounds";
|
|
break;
|
|
case KASAN_GLOBAL_REDZONE:
|
|
bug_type = "global-out-of-bounds";
|
|
break;
|
|
case KASAN_STACK_LEFT:
|
|
case KASAN_STACK_MID:
|
|
case KASAN_STACK_RIGHT:
|
|
case KASAN_STACK_PARTIAL:
|
|
bug_type = "stack-out-of-bounds";
|
|
break;
|
|
case KASAN_FREE_PAGE:
|
|
case KASAN_KMALLOC_FREE:
|
|
bug_type = "use-after-free";
|
|
break;
|
|
case KASAN_ALLOCA_LEFT:
|
|
case KASAN_ALLOCA_RIGHT:
|
|
bug_type = "alloca-out-of-bounds";
|
|
break;
|
|
}
|
|
|
|
return bug_type;
|
|
}
|
|
|
|
static const char *get_wild_bug_type(struct kasan_access_info *info)
|
|
{
|
|
const char *bug_type = "unknown-crash";
|
|
|
|
if ((unsigned long)info->access_addr < PAGE_SIZE)
|
|
bug_type = "null-ptr-deref";
|
|
else if ((unsigned long)info->access_addr < TASK_SIZE)
|
|
bug_type = "user-memory-access";
|
|
else
|
|
bug_type = "wild-memory-access";
|
|
|
|
return bug_type;
|
|
}
|
|
|
|
const char *get_bug_type(struct kasan_access_info *info)
|
|
{
|
|
if (addr_has_shadow(info->access_addr))
|
|
return get_shadow_bug_type(info);
|
|
return get_wild_bug_type(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);
|