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- // SPDX-License-Identifier: GPL-2.0
- /*
- * This file contains core generic KASAN 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/export.h>
- #include <linux/interrupt.h>
- #include <linux/init.h>
- #include <linux/kasan.h>
- #include <linux/kernel.h>
- #include <linux/kfence.h>
- #include <linux/kmemleak.h>
- #include <linux/linkage.h>
- #include <linux/memblock.h>
- #include <linux/memory.h>
- #include <linux/mm.h>
- #include <linux/module.h>
- #include <linux/printk.h>
- #include <linux/sched.h>
- #include <linux/sched/task_stack.h>
- #include <linux/slab.h>
- #include <linux/stacktrace.h>
- #include <linux/string.h>
- #include <linux/types.h>
- #include <linux/vmalloc.h>
- #include <linux/bug.h>
- #include "kasan.h"
- #include "../slab.h"
- /*
- * All functions below always inlined so compiler could
- * perform better optimizations in each of __asan_loadX/__assn_storeX
- * depending on memory access size X.
- */
- static __always_inline bool memory_is_poisoned_1(unsigned long addr)
- {
- s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
- if (unlikely(shadow_value)) {
- s8 last_accessible_byte = addr & KASAN_GRANULE_MASK;
- return unlikely(last_accessible_byte >= shadow_value);
- }
- return false;
- }
- static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
- unsigned long size)
- {
- u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
- /*
- * Access crosses 8(shadow size)-byte boundary. Such access maps
- * into 2 shadow bytes, so we need to check them both.
- */
- if (unlikely(((addr + size - 1) & KASAN_GRANULE_MASK) < size - 1))
- return *shadow_addr || memory_is_poisoned_1(addr + size - 1);
- return memory_is_poisoned_1(addr + size - 1);
- }
- static __always_inline bool memory_is_poisoned_16(unsigned long addr)
- {
- u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
- /* Unaligned 16-bytes access maps into 3 shadow bytes. */
- if (unlikely(!IS_ALIGNED(addr, KASAN_GRANULE_SIZE)))
- return *shadow_addr || memory_is_poisoned_1(addr + 15);
- return *shadow_addr;
- }
- static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
- size_t size)
- {
- while (size) {
- if (unlikely(*start))
- return (unsigned long)start;
- start++;
- size--;
- }
- return 0;
- }
- static __always_inline unsigned long memory_is_nonzero(const void *start,
- const void *end)
- {
- unsigned int words;
- unsigned long ret;
- unsigned int prefix = (unsigned long)start % 8;
- if (end - start <= 16)
- return bytes_is_nonzero(start, end - start);
- if (prefix) {
- prefix = 8 - prefix;
- ret = bytes_is_nonzero(start, prefix);
- if (unlikely(ret))
- return ret;
- start += prefix;
- }
- words = (end - start) / 8;
- while (words) {
- if (unlikely(*(u64 *)start))
- return bytes_is_nonzero(start, 8);
- start += 8;
- words--;
- }
- return bytes_is_nonzero(start, (end - start) % 8);
- }
- static __always_inline bool memory_is_poisoned_n(unsigned long addr,
- size_t size)
- {
- unsigned long ret;
- ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr),
- kasan_mem_to_shadow((void *)addr + size - 1) + 1);
- if (unlikely(ret)) {
- unsigned long last_byte = addr + size - 1;
- s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
- if (unlikely(ret != (unsigned long)last_shadow ||
- ((long)(last_byte & KASAN_GRANULE_MASK) >= *last_shadow)))
- return true;
- }
- return false;
- }
- static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
- {
- if (__builtin_constant_p(size)) {
- switch (size) {
- case 1:
- return memory_is_poisoned_1(addr);
- case 2:
- case 4:
- case 8:
- return memory_is_poisoned_2_4_8(addr, size);
- case 16:
- return memory_is_poisoned_16(addr);
- default:
- BUILD_BUG();
- }
- }
- return memory_is_poisoned_n(addr, size);
- }
- static __always_inline bool check_region_inline(unsigned long addr,
- size_t size, bool write,
- unsigned long ret_ip)
- {
- if (unlikely(size == 0))
- return true;
- if (unlikely(addr + size < addr))
- return !kasan_report(addr, size, write, ret_ip);
- if (unlikely((void *)addr <
- kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
- return !kasan_report(addr, size, write, ret_ip);
- }
- if (likely(!memory_is_poisoned(addr, size)))
- return true;
- return !kasan_report(addr, size, write, ret_ip);
- }
- bool kasan_check_range(unsigned long addr, size_t size, bool write,
- unsigned long ret_ip)
- {
- return check_region_inline(addr, size, write, ret_ip);
- }
- bool kasan_byte_accessible(const void *addr)
- {
- s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr));
- return shadow_byte >= 0 && shadow_byte < KASAN_GRANULE_SIZE;
- }
- void kasan_cache_shrink(struct kmem_cache *cache)
- {
- kasan_quarantine_remove_cache(cache);
- }
- void kasan_cache_shutdown(struct kmem_cache *cache)
- {
- if (!__kmem_cache_empty(cache))
- kasan_quarantine_remove_cache(cache);
- }
- static void register_global(struct kasan_global *global)
- {
- size_t aligned_size = round_up(global->size, KASAN_GRANULE_SIZE);
- kasan_unpoison(global->beg, global->size, false);
- kasan_poison(global->beg + aligned_size,
- global->size_with_redzone - aligned_size,
- KASAN_GLOBAL_REDZONE, false);
- }
- void __asan_register_globals(struct kasan_global *globals, size_t size)
- {
- int i;
- for (i = 0; i < size; i++)
- register_global(&globals[i]);
- }
- EXPORT_SYMBOL(__asan_register_globals);
- void __asan_unregister_globals(struct kasan_global *globals, size_t size)
- {
- }
- EXPORT_SYMBOL(__asan_unregister_globals);
- #define DEFINE_ASAN_LOAD_STORE(size) \
- void __asan_load##size(unsigned long addr) \
- { \
- check_region_inline(addr, size, false, _RET_IP_); \
- } \
- EXPORT_SYMBOL(__asan_load##size); \
- __alias(__asan_load##size) \
- void __asan_load##size##_noabort(unsigned long); \
- EXPORT_SYMBOL(__asan_load##size##_noabort); \
- void __asan_store##size(unsigned long addr) \
- { \
- check_region_inline(addr, size, true, _RET_IP_); \
- } \
- EXPORT_SYMBOL(__asan_store##size); \
- __alias(__asan_store##size) \
- void __asan_store##size##_noabort(unsigned long); \
- EXPORT_SYMBOL(__asan_store##size##_noabort)
- DEFINE_ASAN_LOAD_STORE(1);
- DEFINE_ASAN_LOAD_STORE(2);
- DEFINE_ASAN_LOAD_STORE(4);
- DEFINE_ASAN_LOAD_STORE(8);
- DEFINE_ASAN_LOAD_STORE(16);
- void __asan_loadN(unsigned long addr, size_t size)
- {
- kasan_check_range(addr, size, false, _RET_IP_);
- }
- EXPORT_SYMBOL(__asan_loadN);
- __alias(__asan_loadN)
- void __asan_loadN_noabort(unsigned long, size_t);
- EXPORT_SYMBOL(__asan_loadN_noabort);
- void __asan_storeN(unsigned long addr, size_t size)
- {
- kasan_check_range(addr, size, true, _RET_IP_);
- }
- EXPORT_SYMBOL(__asan_storeN);
- __alias(__asan_storeN)
- void __asan_storeN_noabort(unsigned long, size_t);
- EXPORT_SYMBOL(__asan_storeN_noabort);
- /* to shut up compiler complaints */
- void __asan_handle_no_return(void) {}
- EXPORT_SYMBOL(__asan_handle_no_return);
- /* Emitted by compiler to poison alloca()ed objects. */
- void __asan_alloca_poison(unsigned long addr, size_t size)
- {
- size_t rounded_up_size = round_up(size, KASAN_GRANULE_SIZE);
- size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
- rounded_up_size;
- size_t rounded_down_size = round_down(size, KASAN_GRANULE_SIZE);
- const void *left_redzone = (const void *)(addr -
- KASAN_ALLOCA_REDZONE_SIZE);
- const void *right_redzone = (const void *)(addr + rounded_up_size);
- WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
- kasan_unpoison((const void *)(addr + rounded_down_size),
- size - rounded_down_size, false);
- kasan_poison(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
- KASAN_ALLOCA_LEFT, false);
- kasan_poison(right_redzone, padding_size + KASAN_ALLOCA_REDZONE_SIZE,
- KASAN_ALLOCA_RIGHT, false);
- }
- EXPORT_SYMBOL(__asan_alloca_poison);
- /* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */
- void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom)
- {
- if (unlikely(!stack_top || stack_top > stack_bottom))
- return;
- kasan_unpoison(stack_top, stack_bottom - stack_top, false);
- }
- EXPORT_SYMBOL(__asan_allocas_unpoison);
- /* Emitted by the compiler to [un]poison local variables. */
- #define DEFINE_ASAN_SET_SHADOW(byte) \
- void __asan_set_shadow_##byte(const void *addr, size_t size) \
- { \
- __memset((void *)addr, 0x##byte, size); \
- } \
- EXPORT_SYMBOL(__asan_set_shadow_##byte)
- DEFINE_ASAN_SET_SHADOW(00);
- DEFINE_ASAN_SET_SHADOW(f1);
- DEFINE_ASAN_SET_SHADOW(f2);
- DEFINE_ASAN_SET_SHADOW(f3);
- DEFINE_ASAN_SET_SHADOW(f5);
- DEFINE_ASAN_SET_SHADOW(f8);
- void kasan_record_aux_stack(void *addr)
- {
- struct page *page = kasan_addr_to_page(addr);
- struct kmem_cache *cache;
- struct kasan_alloc_meta *alloc_meta;
- void *object;
- if (is_kfence_address(addr) || !(page && PageSlab(page)))
- return;
- cache = page->slab_cache;
- object = nearest_obj(cache, page, addr);
- alloc_meta = kasan_get_alloc_meta(cache, object);
- if (!alloc_meta)
- return;
- alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0];
- alloc_meta->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);
- }
- void kasan_set_free_info(struct kmem_cache *cache,
- void *object, u8 tag)
- {
- struct kasan_free_meta *free_meta;
- free_meta = kasan_get_free_meta(cache, object);
- if (!free_meta)
- return;
- kasan_set_track(&free_meta->free_track, GFP_NOWAIT);
- /* The object was freed and has free track set. */
- *(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREETRACK;
- }
- struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
- void *object, u8 tag)
- {
- if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_KMALLOC_FREETRACK)
- return NULL;
- /* Free meta must be present with KASAN_KMALLOC_FREETRACK. */
- return &kasan_get_free_meta(cache, object)->free_track;
- }
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