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26e760c9a7
Patch series "kasan: memorize and print call_rcu stack", v8. This patchset improves KASAN reports by making them to have call_rcu() call stack information. It is useful for programmers to solve use-after-free or double-free memory issue. The KASAN report was as follows(cleaned up slightly): BUG: KASAN: use-after-free in kasan_rcu_reclaim+0x58/0x60 Freed by task 0: kasan_save_stack+0x24/0x50 kasan_set_track+0x24/0x38 kasan_set_free_info+0x18/0x20 __kasan_slab_free+0x10c/0x170 kasan_slab_free+0x10/0x18 kfree+0x98/0x270 kasan_rcu_reclaim+0x1c/0x60 Last call_rcu(): kasan_save_stack+0x24/0x50 kasan_record_aux_stack+0xbc/0xd0 call_rcu+0x8c/0x580 kasan_rcu_uaf+0xf4/0xf8 Generic KASAN will record the last two call_rcu() call stacks and print up to 2 call_rcu() call stacks in KASAN report. it is only suitable for generic KASAN. This feature considers the size of struct kasan_alloc_meta and kasan_free_meta, we try to optimize the structure layout and size, lets it get better memory consumption. [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437 [2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ This patch (of 4): This feature will record the last two call_rcu() call stacks and prints up to 2 call_rcu() call stacks in KASAN report. When call_rcu() is called, we store the call_rcu() call stack into slub alloc meta-data, so that the KASAN report can print rcu stack. [1]https://bugzilla.kernel.org/show_bug.cgi?id=198437 [2]https://groups.google.com/forum/#!searchin/kasan-dev/better$20stack$20traces$20for$20rcu%7Csort:date/kasan-dev/KQsjT_88hDE/7rNUZprRBgAJ [walter-zh.wu@mediatek.com: build fix] Link: http://lkml.kernel.org/r/20200710162401.23816-1-walter-zh.wu@mediatek.com Suggested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Walter Wu <walter-zh.wu@mediatek.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Andrey Konovalov <andreyknvl@google.com> Acked-by: Paul E. McKenney <paulmck@kernel.org> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Alexander Potapenko <glider@google.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthias Brugger <matthias.bgg@gmail.com> Link: http://lkml.kernel.org/r/20200710162123.23713-1-walter-zh.wu@mediatek.com Link: http://lkml.kernel.org/r/20200601050847.1096-1-walter-zh.wu@mediatek.com Link: http://lkml.kernel.org/r/20200601050927.1153-1-walter-zh.wu@mediatek.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
348 lines
9.0 KiB
C
348 lines
9.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This file contains core generic KASAN 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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/export.h>
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#include <linux/interrupt.h>
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#include <linux/init.h>
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#include <linux/kasan.h>
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#include <linux/kernel.h>
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#include <linux/kmemleak.h>
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#include <linux/linkage.h>
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#include <linux/memblock.h>
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#include <linux/memory.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/printk.h>
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#include <linux/sched.h>
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#include <linux/sched/task_stack.h>
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#include <linux/slab.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/vmalloc.h>
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#include <linux/bug.h>
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#include "kasan.h"
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#include "../slab.h"
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/*
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* All functions below always inlined so compiler could
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* perform better optimizations in each of __asan_loadX/__assn_storeX
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* depending on memory access size X.
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*/
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static __always_inline bool memory_is_poisoned_1(unsigned long addr)
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{
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s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
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if (unlikely(shadow_value)) {
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s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
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return unlikely(last_accessible_byte >= shadow_value);
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}
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return false;
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}
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static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
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unsigned long size)
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{
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u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
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/*
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* Access crosses 8(shadow size)-byte boundary. Such access maps
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* into 2 shadow bytes, so we need to check them both.
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*/
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if (unlikely(((addr + size - 1) & KASAN_SHADOW_MASK) < size - 1))
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return *shadow_addr || memory_is_poisoned_1(addr + size - 1);
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return memory_is_poisoned_1(addr + size - 1);
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}
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static __always_inline bool memory_is_poisoned_16(unsigned long addr)
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{
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u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
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/* Unaligned 16-bytes access maps into 3 shadow bytes. */
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if (unlikely(!IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
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return *shadow_addr || memory_is_poisoned_1(addr + 15);
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return *shadow_addr;
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}
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static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
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size_t size)
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{
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while (size) {
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if (unlikely(*start))
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return (unsigned long)start;
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start++;
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size--;
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}
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return 0;
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}
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static __always_inline unsigned long memory_is_nonzero(const void *start,
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const void *end)
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{
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unsigned int words;
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unsigned long ret;
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unsigned int prefix = (unsigned long)start % 8;
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if (end - start <= 16)
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return bytes_is_nonzero(start, end - start);
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if (prefix) {
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prefix = 8 - prefix;
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ret = bytes_is_nonzero(start, prefix);
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if (unlikely(ret))
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return ret;
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start += prefix;
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}
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words = (end - start) / 8;
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while (words) {
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if (unlikely(*(u64 *)start))
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return bytes_is_nonzero(start, 8);
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start += 8;
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words--;
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}
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return bytes_is_nonzero(start, (end - start) % 8);
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}
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static __always_inline bool memory_is_poisoned_n(unsigned long addr,
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size_t size)
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{
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unsigned long ret;
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ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr),
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kasan_mem_to_shadow((void *)addr + size - 1) + 1);
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if (unlikely(ret)) {
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unsigned long last_byte = addr + size - 1;
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s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
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if (unlikely(ret != (unsigned long)last_shadow ||
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((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
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return true;
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}
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return false;
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}
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static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
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{
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if (__builtin_constant_p(size)) {
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switch (size) {
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case 1:
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return memory_is_poisoned_1(addr);
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case 2:
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case 4:
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case 8:
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return memory_is_poisoned_2_4_8(addr, size);
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case 16:
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return memory_is_poisoned_16(addr);
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default:
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BUILD_BUG();
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}
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}
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return memory_is_poisoned_n(addr, size);
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}
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static __always_inline bool check_memory_region_inline(unsigned long addr,
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size_t size, bool write,
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unsigned long ret_ip)
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{
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if (unlikely(size == 0))
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return true;
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if (unlikely(addr + size < addr))
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return !kasan_report(addr, size, write, ret_ip);
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if (unlikely((void *)addr <
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kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
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return !kasan_report(addr, size, write, ret_ip);
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}
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if (likely(!memory_is_poisoned(addr, size)))
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return true;
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return !kasan_report(addr, size, write, ret_ip);
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}
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bool check_memory_region(unsigned long addr, size_t size, bool write,
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unsigned long ret_ip)
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{
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return check_memory_region_inline(addr, size, write, ret_ip);
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}
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void kasan_cache_shrink(struct kmem_cache *cache)
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{
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quarantine_remove_cache(cache);
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}
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void kasan_cache_shutdown(struct kmem_cache *cache)
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{
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if (!__kmem_cache_empty(cache))
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quarantine_remove_cache(cache);
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}
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static void register_global(struct kasan_global *global)
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{
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size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
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kasan_unpoison_shadow(global->beg, global->size);
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kasan_poison_shadow(global->beg + aligned_size,
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global->size_with_redzone - aligned_size,
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KASAN_GLOBAL_REDZONE);
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}
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void __asan_register_globals(struct kasan_global *globals, size_t size)
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{
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int i;
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for (i = 0; i < size; i++)
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register_global(&globals[i]);
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}
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EXPORT_SYMBOL(__asan_register_globals);
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void __asan_unregister_globals(struct kasan_global *globals, size_t size)
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{
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}
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EXPORT_SYMBOL(__asan_unregister_globals);
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#define DEFINE_ASAN_LOAD_STORE(size) \
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void __asan_load##size(unsigned long addr) \
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{ \
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check_memory_region_inline(addr, size, false, _RET_IP_);\
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} \
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EXPORT_SYMBOL(__asan_load##size); \
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__alias(__asan_load##size) \
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void __asan_load##size##_noabort(unsigned long); \
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EXPORT_SYMBOL(__asan_load##size##_noabort); \
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void __asan_store##size(unsigned long addr) \
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{ \
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check_memory_region_inline(addr, size, true, _RET_IP_); \
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} \
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EXPORT_SYMBOL(__asan_store##size); \
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__alias(__asan_store##size) \
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void __asan_store##size##_noabort(unsigned long); \
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EXPORT_SYMBOL(__asan_store##size##_noabort)
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DEFINE_ASAN_LOAD_STORE(1);
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DEFINE_ASAN_LOAD_STORE(2);
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DEFINE_ASAN_LOAD_STORE(4);
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DEFINE_ASAN_LOAD_STORE(8);
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DEFINE_ASAN_LOAD_STORE(16);
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void __asan_loadN(unsigned long addr, size_t size)
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{
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check_memory_region(addr, size, false, _RET_IP_);
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}
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EXPORT_SYMBOL(__asan_loadN);
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__alias(__asan_loadN)
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void __asan_loadN_noabort(unsigned long, size_t);
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EXPORT_SYMBOL(__asan_loadN_noabort);
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void __asan_storeN(unsigned long addr, size_t size)
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{
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check_memory_region(addr, size, true, _RET_IP_);
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}
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EXPORT_SYMBOL(__asan_storeN);
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__alias(__asan_storeN)
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void __asan_storeN_noabort(unsigned long, size_t);
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EXPORT_SYMBOL(__asan_storeN_noabort);
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/* to shut up compiler complaints */
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void __asan_handle_no_return(void) {}
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EXPORT_SYMBOL(__asan_handle_no_return);
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/* Emitted by compiler to poison alloca()ed objects. */
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void __asan_alloca_poison(unsigned long addr, size_t size)
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{
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size_t rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
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size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
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rounded_up_size;
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size_t rounded_down_size = round_down(size, KASAN_SHADOW_SCALE_SIZE);
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const void *left_redzone = (const void *)(addr -
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KASAN_ALLOCA_REDZONE_SIZE);
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const void *right_redzone = (const void *)(addr + rounded_up_size);
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WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
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kasan_unpoison_shadow((const void *)(addr + rounded_down_size),
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size - rounded_down_size);
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kasan_poison_shadow(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
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KASAN_ALLOCA_LEFT);
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kasan_poison_shadow(right_redzone,
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padding_size + KASAN_ALLOCA_REDZONE_SIZE,
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KASAN_ALLOCA_RIGHT);
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}
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EXPORT_SYMBOL(__asan_alloca_poison);
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/* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */
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void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom)
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{
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if (unlikely(!stack_top || stack_top > stack_bottom))
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return;
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kasan_unpoison_shadow(stack_top, stack_bottom - stack_top);
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}
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EXPORT_SYMBOL(__asan_allocas_unpoison);
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/* Emitted by the compiler to [un]poison local variables. */
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#define DEFINE_ASAN_SET_SHADOW(byte) \
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void __asan_set_shadow_##byte(const void *addr, size_t size) \
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{ \
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__memset((void *)addr, 0x##byte, size); \
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} \
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EXPORT_SYMBOL(__asan_set_shadow_##byte)
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DEFINE_ASAN_SET_SHADOW(00);
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DEFINE_ASAN_SET_SHADOW(f1);
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DEFINE_ASAN_SET_SHADOW(f2);
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DEFINE_ASAN_SET_SHADOW(f3);
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DEFINE_ASAN_SET_SHADOW(f5);
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DEFINE_ASAN_SET_SHADOW(f8);
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void kasan_record_aux_stack(void *addr)
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{
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struct page *page = kasan_addr_to_page(addr);
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struct kmem_cache *cache;
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struct kasan_alloc_meta *alloc_info;
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void *object;
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if (!(page && PageSlab(page)))
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return;
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cache = page->slab_cache;
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object = nearest_obj(cache, page, addr);
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alloc_info = get_alloc_info(cache, object);
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/*
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* record the last two call_rcu() call stacks.
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*/
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alloc_info->aux_stack[1] = alloc_info->aux_stack[0];
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alloc_info->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);
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}
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