// SPDX-License-Identifier: GPL-2.0
/*
- * This file contains common generic and tag-based KASAN code.
+ * This file contains common 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>
- *
- * 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/export.h>
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
-#include <linux/kmemleak.h>
#include <linux/linkage.h>
#include <linux/memblock.h>
#include <linux/memory.h>
#include <linux/stacktrace.h>
#include <linux/string.h>
#include <linux/types.h>
-#include <linux/vmalloc.h>
#include <linux/bug.h>
-#include <asm/cacheflush.h>
-#include <asm/tlbflush.h>
-
#include "kasan.h"
#include "../slab.h"
track->stack = kasan_save_stack(flags);
}
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
void kasan_enable_current(void)
{
current->kasan_depth++;
{
current->kasan_depth--;
}
+#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
-bool __kasan_check_read(const volatile void *p, unsigned int size)
-{
- return check_memory_region((unsigned long)p, size, false, _RET_IP_);
-}
-EXPORT_SYMBOL(__kasan_check_read);
-
-bool __kasan_check_write(const volatile void *p, unsigned int size)
-{
- return check_memory_region((unsigned long)p, size, true, _RET_IP_);
-}
-EXPORT_SYMBOL(__kasan_check_write);
-
-#undef memset
-void *memset(void *addr, int c, size_t len)
-{
- if (!check_memory_region((unsigned long)addr, len, true, _RET_IP_))
- return NULL;
-
- return __memset(addr, c, len);
-}
-
-#ifdef __HAVE_ARCH_MEMMOVE
-#undef memmove
-void *memmove(void *dest, const void *src, size_t len)
-{
- if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) ||
- !check_memory_region((unsigned long)dest, len, true, _RET_IP_))
- return NULL;
-
- return __memmove(dest, src, len);
-}
-#endif
-
-#undef memcpy
-void *memcpy(void *dest, const void *src, size_t len)
+void __kasan_unpoison_range(const void *address, size_t size)
{
- if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) ||
- !check_memory_region((unsigned long)dest, len, true, _RET_IP_))
- return NULL;
-
- return __memcpy(dest, src, len);
-}
-
-/*
- * Poisons the shadow memory for 'size' bytes starting from 'addr'.
- * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
- */
-void kasan_poison_shadow(const void *address, size_t size, u8 value)
-{
- void *shadow_start, *shadow_end;
-
- /*
- * Perform shadow offset calculation based on untagged address, as
- * some of the callers (e.g. kasan_poison_object_data) pass tagged
- * addresses to this function.
- */
- address = reset_tag(address);
-
- shadow_start = kasan_mem_to_shadow(address);
- shadow_end = kasan_mem_to_shadow(address + size);
-
- __memset(shadow_start, value, shadow_end - shadow_start);
-}
-
-void kasan_unpoison_shadow(const void *address, size_t size)
-{
- u8 tag = get_tag(address);
-
- /*
- * Perform shadow offset calculation based on untagged address, as
- * some of the callers (e.g. kasan_unpoison_object_data) pass tagged
- * addresses to this function.
- */
- address = reset_tag(address);
-
- kasan_poison_shadow(address, size, tag);
-
- if (size & KASAN_SHADOW_MASK) {
- u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
-
- if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
- *shadow = tag;
- else
- *shadow = size & KASAN_SHADOW_MASK;
- }
-}
-
-static void __kasan_unpoison_stack(struct task_struct *task, const void *sp)
-{
- void *base = task_stack_page(task);
- size_t size = sp - base;
-
- kasan_unpoison_shadow(base, size);
+ unpoison_range(address, size);
}
+#if CONFIG_KASAN_STACK
/* Unpoison the entire stack for a task. */
void kasan_unpoison_task_stack(struct task_struct *task)
{
- __kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE);
+ void *base = task_stack_page(task);
+
+ unpoison_range(base, THREAD_SIZE);
}
/* Unpoison the stack for the current task beyond a watermark sp value. */
*/
void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
- kasan_unpoison_shadow(base, watermark - base);
+ unpoison_range(base, watermark - base);
+}
+#endif /* CONFIG_KASAN_STACK */
+
+/*
+ * Only allow cache merging when stack collection is disabled and no metadata
+ * is present.
+ */
+slab_flags_t __kasan_never_merge(void)
+{
+ if (kasan_stack_collection_enabled())
+ return SLAB_KASAN;
+ return 0;
}
-void kasan_alloc_pages(struct page *page, unsigned int order)
+void __kasan_alloc_pages(struct page *page, unsigned int order)
{
u8 tag;
unsigned long i;
tag = random_tag();
for (i = 0; i < (1 << order); i++)
page_kasan_tag_set(page + i, tag);
- kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
+ unpoison_range(page_address(page), PAGE_SIZE << order);
}
-void kasan_free_pages(struct page *page, unsigned int order)
+void __kasan_free_pages(struct page *page, unsigned int order)
{
if (likely(!PageHighMem(page)))
- kasan_poison_shadow(page_address(page),
+ poison_range(page_address(page),
PAGE_SIZE << order,
KASAN_FREE_PAGE);
}
*/
static inline unsigned int optimal_redzone(unsigned int object_size)
{
- if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
- return 0;
-
return
object_size <= 64 - 16 ? 16 :
object_size <= 128 - 32 ? 32 :
object_size <= (1 << 16) - 1024 ? 1024 : 2048;
}
-void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
- slab_flags_t *flags)
+void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
+ slab_flags_t *flags)
{
- unsigned int orig_size = *size;
- unsigned int redzone_size;
- int redzone_adjust;
+ unsigned int ok_size;
+ unsigned int optimal_size;
- /* Add alloc meta. */
- cache->kasan_info.alloc_meta_offset = *size;
- *size += sizeof(struct kasan_alloc_meta);
+ /*
+ * SLAB_KASAN is used to mark caches as ones that are sanitized by
+ * KASAN. Currently this flag is used in two places:
+ * 1. In slab_ksize() when calculating the size of the accessible
+ * memory within the object.
+ * 2. In slab_common.c to prevent merging of sanitized caches.
+ */
+ *flags |= SLAB_KASAN;
- /* Add free meta. */
- if (IS_ENABLED(CONFIG_KASAN_GENERIC) &&
- (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor ||
- cache->object_size < sizeof(struct kasan_free_meta))) {
- cache->kasan_info.free_meta_offset = *size;
- *size += sizeof(struct kasan_free_meta);
- }
+ if (!kasan_stack_collection_enabled())
+ return;
- redzone_size = optimal_redzone(cache->object_size);
- redzone_adjust = redzone_size - (*size - cache->object_size);
- if (redzone_adjust > 0)
- *size += redzone_adjust;
+ ok_size = *size;
- *size = min_t(unsigned int, KMALLOC_MAX_SIZE,
- max(*size, cache->object_size + redzone_size));
+ /* Add alloc meta into redzone. */
+ cache->kasan_info.alloc_meta_offset = *size;
+ *size += sizeof(struct kasan_alloc_meta);
/*
- * If the metadata doesn't fit, don't enable KASAN at all.
+ * If alloc meta doesn't fit, don't add it.
+ * This can only happen with SLAB, as it has KMALLOC_MAX_SIZE equal
+ * to KMALLOC_MAX_CACHE_SIZE and doesn't fall back to page_alloc for
+ * larger sizes.
*/
- if (*size <= cache->kasan_info.alloc_meta_offset ||
- *size <= cache->kasan_info.free_meta_offset) {
+ if (*size > KMALLOC_MAX_SIZE) {
cache->kasan_info.alloc_meta_offset = 0;
- cache->kasan_info.free_meta_offset = 0;
- *size = orig_size;
+ *size = ok_size;
+ /* Continue, since free meta might still fit. */
+ }
+
+ /* Only the generic mode uses free meta or flexible redzones. */
+ if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) {
+ cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
return;
}
- *flags |= SLAB_KASAN;
+ /*
+ * Add free meta into redzone when it's not possible to store
+ * it in the object. This is the case when:
+ * 1. Object is SLAB_TYPESAFE_BY_RCU, which means that it can
+ * be touched after it was freed, or
+ * 2. Object has a constructor, which means it's expected to
+ * retain its content until the next allocation, or
+ * 3. Object is too small.
+ * Otherwise cache->kasan_info.free_meta_offset = 0 is implied.
+ */
+ if ((cache->flags & SLAB_TYPESAFE_BY_RCU) || cache->ctor ||
+ cache->object_size < sizeof(struct kasan_free_meta)) {
+ ok_size = *size;
+
+ cache->kasan_info.free_meta_offset = *size;
+ *size += sizeof(struct kasan_free_meta);
+
+ /* If free meta doesn't fit, don't add it. */
+ if (*size > KMALLOC_MAX_SIZE) {
+ cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
+ *size = ok_size;
+ }
+ }
+
+ /* Calculate size with optimal redzone. */
+ optimal_size = cache->object_size + optimal_redzone(cache->object_size);
+ /* Limit it with KMALLOC_MAX_SIZE (relevant for SLAB only). */
+ if (optimal_size > KMALLOC_MAX_SIZE)
+ optimal_size = KMALLOC_MAX_SIZE;
+ /* Use optimal size if the size with added metas is not large enough. */
+ if (*size < optimal_size)
+ *size = optimal_size;
}
-size_t kasan_metadata_size(struct kmem_cache *cache)
+size_t __kasan_metadata_size(struct kmem_cache *cache)
{
+ if (!kasan_stack_collection_enabled())
+ return 0;
return (cache->kasan_info.alloc_meta_offset ?
sizeof(struct kasan_alloc_meta) : 0) +
(cache->kasan_info.free_meta_offset ?
sizeof(struct kasan_free_meta) : 0);
}
-struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
- const void *object)
+struct kasan_alloc_meta *kasan_get_alloc_meta(struct kmem_cache *cache,
+ const void *object)
{
- return (void *)object + cache->kasan_info.alloc_meta_offset;
+ if (!cache->kasan_info.alloc_meta_offset)
+ return NULL;
+ return kasan_reset_tag(object) + cache->kasan_info.alloc_meta_offset;
}
-struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
- const void *object)
+#ifdef CONFIG_KASAN_GENERIC
+struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
+ const void *object)
{
BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32);
- return (void *)object + cache->kasan_info.free_meta_offset;
+ if (cache->kasan_info.free_meta_offset == KASAN_NO_FREE_META)
+ return NULL;
+ return kasan_reset_tag(object) + cache->kasan_info.free_meta_offset;
}
+#endif
-void kasan_poison_slab(struct page *page)
+void __kasan_poison_slab(struct page *page)
{
unsigned long i;
for (i = 0; i < compound_nr(page); i++)
page_kasan_tag_reset(page + i);
- kasan_poison_shadow(page_address(page), page_size(page),
- KASAN_KMALLOC_REDZONE);
+ poison_range(page_address(page), page_size(page),
+ KASAN_KMALLOC_REDZONE);
}
-void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
+void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
{
- kasan_unpoison_shadow(object, cache->object_size);
+ unpoison_range(object, cache->object_size);
}
-void kasan_poison_object_data(struct kmem_cache *cache, void *object)
+void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
{
- kasan_poison_shadow(object,
- round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
- KASAN_KMALLOC_REDZONE);
+ poison_range(object, cache->object_size, KASAN_KMALLOC_REDZONE);
}
/*
static u8 assign_tag(struct kmem_cache *cache, const void *object,
bool init, bool keep_tag)
{
+ if (IS_ENABLED(CONFIG_KASAN_GENERIC))
+ return 0xff;
+
/*
* 1. When an object is kmalloc()'ed, two hooks are called:
* kasan_slab_alloc() and kasan_kmalloc(). We assign the
#endif
}
-void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
+void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
const void *object)
{
- struct kasan_alloc_meta *alloc_info;
+ struct kasan_alloc_meta *alloc_meta;
- if (!(cache->flags & SLAB_KASAN))
- return (void *)object;
-
- alloc_info = get_alloc_info(cache, object);
- __memset(alloc_info, 0, sizeof(*alloc_info));
+ if (kasan_stack_collection_enabled()) {
+ alloc_meta = kasan_get_alloc_meta(cache, object);
+ if (alloc_meta)
+ __memset(alloc_meta, 0, sizeof(*alloc_meta));
+ }
- if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
- object = set_tag(object,
- assign_tag(cache, object, true, false));
+ /* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */
+ object = set_tag(object, assign_tag(cache, object, true, false));
return (void *)object;
}
-static inline bool shadow_invalid(u8 tag, s8 shadow_byte)
-{
- if (IS_ENABLED(CONFIG_KASAN_GENERIC))
- return shadow_byte < 0 ||
- shadow_byte >= KASAN_SHADOW_SCALE_SIZE;
-
- /* else CONFIG_KASAN_SW_TAGS: */
- if ((u8)shadow_byte == KASAN_TAG_INVALID)
- return true;
- if ((tag != KASAN_TAG_KERNEL) && (tag != (u8)shadow_byte))
- return true;
-
- return false;
-}
-
-static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
+static bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
unsigned long ip, bool quarantine)
{
- s8 shadow_byte;
u8 tag;
void *tagged_object;
- unsigned long rounded_up_size;
tag = get_tag(object);
tagged_object = object;
- object = reset_tag(object);
+ object = kasan_reset_tag(object);
if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) !=
object)) {
if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
return false;
- shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
- if (shadow_invalid(tag, shadow_byte)) {
+ if (check_invalid_free(tagged_object)) {
kasan_report_invalid_free(tagged_object, ip);
return true;
}
- rounded_up_size = round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE);
- kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
+ poison_range(object, cache->object_size, KASAN_KMALLOC_FREE);
- if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) ||
- unlikely(!(cache->flags & SLAB_KASAN)))
+ if (!kasan_stack_collection_enabled())
+ return false;
+
+ if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine))
return false;
kasan_set_free_info(cache, object, tag);
- quarantine_put(get_free_info(cache, object), cache);
+ return quarantine_put(cache, object);
+}
- return IS_ENABLED(CONFIG_KASAN_GENERIC);
+bool __kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
+{
+ return ____kasan_slab_free(cache, object, ip, true);
}
-bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
+void __kasan_slab_free_mempool(void *ptr, unsigned long ip)
{
- return __kasan_slab_free(cache, object, ip, true);
+ struct page *page;
+
+ page = virt_to_head_page(ptr);
+
+ /*
+ * Even though this function is only called for kmem_cache_alloc and
+ * kmalloc backed mempool allocations, those allocations can still be
+ * !PageSlab() when the size provided to kmalloc is larger than
+ * KMALLOC_MAX_SIZE, and kmalloc falls back onto page_alloc.
+ */
+ if (unlikely(!PageSlab(page))) {
+ if (ptr != page_address(page)) {
+ kasan_report_invalid_free(ptr, ip);
+ return;
+ }
+ poison_range(ptr, page_size(page), KASAN_FREE_PAGE);
+ } else {
+ ____kasan_slab_free(page->slab_cache, ptr, ip, false);
+ }
+}
+
+static void set_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
+{
+ struct kasan_alloc_meta *alloc_meta;
+
+ alloc_meta = kasan_get_alloc_meta(cache, object);
+ if (alloc_meta)
+ kasan_set_track(&alloc_meta->alloc_track, flags);
}
-static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
+static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
size_t size, gfp_t flags, bool keep_tag)
{
unsigned long redzone_start;
unsigned long redzone_end;
- u8 tag = 0xff;
+ u8 tag;
if (gfpflags_allow_blocking(flags))
quarantine_reduce();
return NULL;
redzone_start = round_up((unsigned long)(object + size),
- KASAN_SHADOW_SCALE_SIZE);
+ KASAN_GRANULE_SIZE);
redzone_end = round_up((unsigned long)object + cache->object_size,
- KASAN_SHADOW_SCALE_SIZE);
-
- if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
- tag = assign_tag(cache, object, false, keep_tag);
+ KASAN_GRANULE_SIZE);
+ tag = assign_tag(cache, object, false, keep_tag);
- /* Tag is ignored in set_tag without CONFIG_KASAN_SW_TAGS */
- kasan_unpoison_shadow(set_tag(object, tag), size);
- kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
- KASAN_KMALLOC_REDZONE);
+ /* Tag is ignored in set_tag without CONFIG_KASAN_SW/HW_TAGS */
+ unpoison_range(set_tag(object, tag), size);
+ poison_range((void *)redzone_start, redzone_end - redzone_start,
+ KASAN_KMALLOC_REDZONE);
- if (cache->flags & SLAB_KASAN)
- kasan_set_track(&get_alloc_info(cache, object)->alloc_track, flags);
+ if (kasan_stack_collection_enabled())
+ set_alloc_info(cache, (void *)object, flags);
return set_tag(object, tag);
}
-void * __must_check kasan_slab_alloc(struct kmem_cache *cache, void *object,
- gfp_t flags)
+void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
+ void *object, gfp_t flags)
{
- return __kasan_kmalloc(cache, object, cache->object_size, flags, false);
+ return ____kasan_kmalloc(cache, object, cache->object_size, flags, false);
}
-void * __must_check kasan_kmalloc(struct kmem_cache *cache, const void *object,
- size_t size, gfp_t flags)
+void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object,
+ size_t size, gfp_t flags)
{
- return __kasan_kmalloc(cache, object, size, flags, true);
+ return ____kasan_kmalloc(cache, object, size, flags, true);
}
-EXPORT_SYMBOL(kasan_kmalloc);
+EXPORT_SYMBOL(__kasan_kmalloc);
-void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
+void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size,
gfp_t flags)
{
struct page *page;
page = virt_to_page(ptr);
redzone_start = round_up((unsigned long)(ptr + size),
- KASAN_SHADOW_SCALE_SIZE);
+ KASAN_GRANULE_SIZE);
redzone_end = (unsigned long)ptr + page_size(page);
- kasan_unpoison_shadow(ptr, size);
- kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
- KASAN_PAGE_REDZONE);
+ unpoison_range(ptr, size);
+ poison_range((void *)redzone_start, redzone_end - redzone_start,
+ KASAN_PAGE_REDZONE);
return (void *)ptr;
}
-void * __must_check kasan_krealloc(const void *object, size_t size, gfp_t flags)
+void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags)
{
struct page *page;
page = virt_to_head_page(object);
if (unlikely(!PageSlab(page)))
- return kasan_kmalloc_large(object, size, flags);
+ return __kasan_kmalloc_large(object, size, flags);
else
- return __kasan_kmalloc(page->slab_cache, object, size,
+ return ____kasan_kmalloc(page->slab_cache, object, size,
flags, true);
}
-void kasan_poison_kfree(void *ptr, unsigned long ip)
-{
- struct page *page;
-
- page = virt_to_head_page(ptr);
-
- if (unlikely(!PageSlab(page))) {
- if (ptr != page_address(page)) {
- kasan_report_invalid_free(ptr, ip);
- return;
- }
- kasan_poison_shadow(ptr, page_size(page), KASAN_FREE_PAGE);
- } else {
- __kasan_slab_free(page->slab_cache, ptr, ip, false);
- }
-}
-
-void kasan_kfree_large(void *ptr, unsigned long ip)
+void __kasan_kfree_large(void *ptr, unsigned long ip)
{
if (ptr != page_address(virt_to_head_page(ptr)))
kasan_report_invalid_free(ptr, ip);
- /* The object will be poisoned by page_alloc. */
-}
-
-#ifndef CONFIG_KASAN_VMALLOC
-int kasan_module_alloc(void *addr, size_t size)
-{
- void *ret;
- size_t scaled_size;
- size_t shadow_size;
- unsigned long shadow_start;
-
- shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
- scaled_size = (size + KASAN_SHADOW_MASK) >> KASAN_SHADOW_SCALE_SHIFT;
- shadow_size = round_up(scaled_size, PAGE_SIZE);
-
- if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
- return -EINVAL;
-
- ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
- shadow_start + shadow_size,
- GFP_KERNEL,
- PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
- __builtin_return_address(0));
-
- if (ret) {
- __memset(ret, KASAN_SHADOW_INIT, shadow_size);
- find_vm_area(addr)->flags |= VM_KASAN;
- kmemleak_ignore(ret);
- return 0;
- }
-
- return -ENOMEM;
-}
-
-void kasan_free_shadow(const struct vm_struct *vm)
-{
- if (vm->flags & VM_KASAN)
- vfree(kasan_mem_to_shadow(vm->addr));
-}
-#endif
-
-#ifdef CONFIG_MEMORY_HOTPLUG
-static bool shadow_mapped(unsigned long addr)
-{
- pgd_t *pgd = pgd_offset_k(addr);
- p4d_t *p4d;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *pte;
-
- if (pgd_none(*pgd))
- return false;
- p4d = p4d_offset(pgd, addr);
- if (p4d_none(*p4d))
- return false;
- pud = pud_offset(p4d, addr);
- if (pud_none(*pud))
- return false;
-
- /*
- * We can't use pud_large() or pud_huge(), the first one is
- * arch-specific, the last one depends on HUGETLB_PAGE. So let's abuse
- * pud_bad(), if pud is bad then it's bad because it's huge.
- */
- if (pud_bad(*pud))
- return true;
- pmd = pmd_offset(pud, addr);
- if (pmd_none(*pmd))
- return false;
-
- if (pmd_bad(*pmd))
- return true;
- pte = pte_offset_kernel(pmd, addr);
- return !pte_none(*pte);
-}
-
-static int __meminit kasan_mem_notifier(struct notifier_block *nb,
- unsigned long action, void *data)
-{
- struct memory_notify *mem_data = data;
- unsigned long nr_shadow_pages, start_kaddr, shadow_start;
- unsigned long shadow_end, shadow_size;
-
- nr_shadow_pages = mem_data->nr_pages >> KASAN_SHADOW_SCALE_SHIFT;
- start_kaddr = (unsigned long)pfn_to_kaddr(mem_data->start_pfn);
- shadow_start = (unsigned long)kasan_mem_to_shadow((void *)start_kaddr);
- shadow_size = nr_shadow_pages << PAGE_SHIFT;
- shadow_end = shadow_start + shadow_size;
-
- if (WARN_ON(mem_data->nr_pages % KASAN_SHADOW_SCALE_SIZE) ||
- WARN_ON(start_kaddr % (KASAN_SHADOW_SCALE_SIZE << PAGE_SHIFT)))
- return NOTIFY_BAD;
-
- switch (action) {
- case MEM_GOING_ONLINE: {
- void *ret;
-
- /*
- * If shadow is mapped already than it must have been mapped
- * during the boot. This could happen if we onlining previously
- * offlined memory.
- */
- if (shadow_mapped(shadow_start))
- return NOTIFY_OK;
-
- ret = __vmalloc_node_range(shadow_size, PAGE_SIZE, shadow_start,
- shadow_end, GFP_KERNEL,
- PAGE_KERNEL, VM_NO_GUARD,
- pfn_to_nid(mem_data->start_pfn),
- __builtin_return_address(0));
- if (!ret)
- return NOTIFY_BAD;
-
- kmemleak_ignore(ret);
- return NOTIFY_OK;
- }
- case MEM_CANCEL_ONLINE:
- case MEM_OFFLINE: {
- struct vm_struct *vm;
-
- /*
- * shadow_start was either mapped during boot by kasan_init()
- * or during memory online by __vmalloc_node_range().
- * In the latter case we can use vfree() to free shadow.
- * Non-NULL result of the find_vm_area() will tell us if
- * that was the second case.
- *
- * Currently it's not possible to free shadow mapped
- * during boot by kasan_init(). It's because the code
- * to do that hasn't been written yet. So we'll just
- * leak the memory.
- */
- vm = find_vm_area((void *)shadow_start);
- if (vm)
- vfree((void *)shadow_start);
- }
- }
-
- return NOTIFY_OK;
-}
-
-static int __init kasan_memhotplug_init(void)
-{
- hotplug_memory_notifier(kasan_mem_notifier, 0);
-
- return 0;
-}
-
-core_initcall(kasan_memhotplug_init);
-#endif
-
-#ifdef CONFIG_KASAN_VMALLOC
-static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr,
- void *unused)
-{
- unsigned long page;
- pte_t pte;
-
- if (likely(!pte_none(*ptep)))
- return 0;
-
- page = __get_free_page(GFP_KERNEL);
- if (!page)
- return -ENOMEM;
-
- memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE);
- pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL);
-
- spin_lock(&init_mm.page_table_lock);
- if (likely(pte_none(*ptep))) {
- set_pte_at(&init_mm, addr, ptep, pte);
- page = 0;
- }
- spin_unlock(&init_mm.page_table_lock);
- if (page)
- free_page(page);
- return 0;
-}
-
-int kasan_populate_vmalloc(unsigned long addr, unsigned long size)
-{
- unsigned long shadow_start, shadow_end;
- int ret;
-
- if (!is_vmalloc_or_module_addr((void *)addr))
- return 0;
-
- shadow_start = (unsigned long)kasan_mem_to_shadow((void *)addr);
- shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE);
- shadow_end = (unsigned long)kasan_mem_to_shadow((void *)addr + size);
- shadow_end = ALIGN(shadow_end, PAGE_SIZE);
-
- ret = apply_to_page_range(&init_mm, shadow_start,
- shadow_end - shadow_start,
- kasan_populate_vmalloc_pte, NULL);
- if (ret)
- return ret;
-
- flush_cache_vmap(shadow_start, shadow_end);
-
- /*
- * We need to be careful about inter-cpu effects here. Consider:
- *
- * CPU#0 CPU#1
- * WRITE_ONCE(p, vmalloc(100)); while (x = READ_ONCE(p)) ;
- * p[99] = 1;
- *
- * With compiler instrumentation, that ends up looking like this:
- *
- * CPU#0 CPU#1
- * // vmalloc() allocates memory
- * // let a = area->addr
- * // we reach kasan_populate_vmalloc
- * // and call kasan_unpoison_shadow:
- * STORE shadow(a), unpoison_val
- * ...
- * STORE shadow(a+99), unpoison_val x = LOAD p
- * // rest of vmalloc process <data dependency>
- * STORE p, a LOAD shadow(x+99)
- *
- * If there is no barrier between the end of unpoisioning the shadow
- * and the store of the result to p, the stores could be committed
- * in a different order by CPU#0, and CPU#1 could erroneously observe
- * poison in the shadow.
- *
- * We need some sort of barrier between the stores.
- *
- * In the vmalloc() case, this is provided by a smp_wmb() in
- * clear_vm_uninitialized_flag(). In the per-cpu allocator and in
- * get_vm_area() and friends, the caller gets shadow allocated but
- * doesn't have any pages mapped into the virtual address space that
- * has been reserved. Mapping those pages in will involve taking and
- * releasing a page-table lock, which will provide the barrier.
- */
-
- return 0;
-}
-
-/*
- * Poison the shadow for a vmalloc region. Called as part of the
- * freeing process at the time the region is freed.
- */
-void kasan_poison_vmalloc(const void *start, unsigned long size)
-{
- if (!is_vmalloc_or_module_addr(start))
- return;
-
- size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
- kasan_poison_shadow(start, size, KASAN_VMALLOC_INVALID);
-}
-
-void kasan_unpoison_vmalloc(const void *start, unsigned long size)
-{
- if (!is_vmalloc_or_module_addr(start))
- return;
-
- kasan_unpoison_shadow(start, size);
+ /* The object will be poisoned by kasan_free_pages(). */
}
-
-static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr,
- void *unused)
-{
- unsigned long page;
-
- page = (unsigned long)__va(pte_pfn(*ptep) << PAGE_SHIFT);
-
- spin_lock(&init_mm.page_table_lock);
-
- if (likely(!pte_none(*ptep))) {
- pte_clear(&init_mm, addr, ptep);
- free_page(page);
- }
- spin_unlock(&init_mm.page_table_lock);
-
- return 0;
-}
-
-/*
- * Release the backing for the vmalloc region [start, end), which
- * lies within the free region [free_region_start, free_region_end).
- *
- * This can be run lazily, long after the region was freed. It runs
- * under vmap_area_lock, so it's not safe to interact with the vmalloc/vmap
- * infrastructure.
- *
- * How does this work?
- * -------------------
- *
- * We have a region that is page aligned, labelled as A.
- * That might not map onto the shadow in a way that is page-aligned:
- *
- * start end
- * v v
- * |????????|????????|AAAAAAAA|AA....AA|AAAAAAAA|????????| < vmalloc
- * -------- -------- -------- -------- --------
- * | | | | |
- * | | | /-------/ |
- * \-------\|/------/ |/---------------/
- * ||| ||
- * |??AAAAAA|AAAAAAAA|AA??????| < shadow
- * (1) (2) (3)
- *
- * First we align the start upwards and the end downwards, so that the
- * shadow of the region aligns with shadow page boundaries. In the
- * example, this gives us the shadow page (2). This is the shadow entirely
- * covered by this allocation.
- *
- * Then we have the tricky bits. We want to know if we can free the
- * partially covered shadow pages - (1) and (3) in the example. For this,
- * we are given the start and end of the free region that contains this
- * allocation. Extending our previous example, we could have:
- *
- * free_region_start free_region_end
- * | start end |
- * v v v v
- * |FFFFFFFF|FFFFFFFF|AAAAAAAA|AA....AA|AAAAAAAA|FFFFFFFF| < vmalloc
- * -------- -------- -------- -------- --------
- * | | | | |
- * | | | /-------/ |
- * \-------\|/------/ |/---------------/
- * ||| ||
- * |FFAAAAAA|AAAAAAAA|AAF?????| < shadow
- * (1) (2) (3)
- *
- * Once again, we align the start of the free region up, and the end of
- * the free region down so that the shadow is page aligned. So we can free
- * page (1) - we know no allocation currently uses anything in that page,
- * because all of it is in the vmalloc free region. But we cannot free
- * page (3), because we can't be sure that the rest of it is unused.
- *
- * We only consider pages that contain part of the original region for
- * freeing: we don't try to free other pages from the free region or we'd
- * end up trying to free huge chunks of virtual address space.
- *
- * Concurrency
- * -----------
- *
- * How do we know that we're not freeing a page that is simultaneously
- * being used for a fresh allocation in kasan_populate_vmalloc(_pte)?
- *
- * We _can_ have kasan_release_vmalloc and kasan_populate_vmalloc running
- * at the same time. While we run under free_vmap_area_lock, the population
- * code does not.
- *
- * free_vmap_area_lock instead operates to ensure that the larger range
- * [free_region_start, free_region_end) is safe: because __alloc_vmap_area and
- * the per-cpu region-finding algorithm both run under free_vmap_area_lock,
- * no space identified as free will become used while we are running. This
- * means that so long as we are careful with alignment and only free shadow
- * pages entirely covered by the free region, we will not run in to any
- * trouble - any simultaneous allocations will be for disjoint regions.
- */
-void kasan_release_vmalloc(unsigned long start, unsigned long end,
- unsigned long free_region_start,
- unsigned long free_region_end)
-{
- void *shadow_start, *shadow_end;
- unsigned long region_start, region_end;
- unsigned long size;
-
- region_start = ALIGN(start, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE);
- region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE);
-
- free_region_start = ALIGN(free_region_start,
- PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE);
-
- if (start != region_start &&
- free_region_start < region_start)
- region_start -= PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE;
-
- free_region_end = ALIGN_DOWN(free_region_end,
- PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE);
-
- if (end != region_end &&
- free_region_end > region_end)
- region_end += PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE;
-
- shadow_start = kasan_mem_to_shadow((void *)region_start);
- shadow_end = kasan_mem_to_shadow((void *)region_end);
-
- if (shadow_end > shadow_start) {
- size = shadow_end - shadow_start;
- apply_to_existing_page_range(&init_mm,
- (unsigned long)shadow_start,
- size, kasan_depopulate_vmalloc_pte,
- NULL);
- flush_tlb_kernel_range((unsigned long)shadow_start,
- (unsigned long)shadow_end);
- }
-}
-#endif
projects / linux-2.6-microblaze.git / blobdiff