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kasan: record and print the free track

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Move free track from kasan_alloc_meta to kasan_free_meta in order to make
struct kasan_alloc_meta and kasan_free_meta size are both 16 bytes.  It is
a good size because it is the minimal redzone size and a good number of
alignment.

For free track, we make some modifications as shown below:
1) Remove the free_track from struct kasan_alloc_meta.
2) Add the free_track into struct kasan_free_meta.
3) Add a macro KASAN_KMALLOC_FREETRACK in order to check whether
   it can print free stack in KASAN report.

[1]https://bugzilla.kernel.org/show_bug.cgi?id=198437

[walter-zh.wu@mediatek.com: build fix]
  Link: http://lkml.kernel.org/r/20200710162440.23887-1-walter-zh.wu@mediatek.com

Suggested-by: Dmitry Vyukov <dvyukov@google.com>
Co-developed-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>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Link: http://lkml.kernel.org/r/20200601051022.1230-1-walter-zh.wu@mediatek.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Walter Wu 2020-08-06 23:24:39 -07:00 committed by Linus Torvalds
parent 26e760c9a7
commit e4b7818b9a
7 changed files with 80 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
mm/kasan/common.c
View File

@ -50,7 +50,7 @@ depot_stack_handle_t kasan_save_stack(gfp_t flags)
return stack_depot_save(entries, nr_entries, flags);
}
static inline void set_track(struct kasan_track *track, gfp_t flags)
void kasan_set_track(struct kasan_track *track, gfp_t flags)
{
track->pid = current->pid;
track->stack = kasan_save_stack(flags);
@ -298,24 +298,6 @@ struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
return (void *)object + cache->kasan_info.free_meta_offset;
}
static void kasan_set_free_info(struct kmem_cache *cache,
void *object, u8 tag)
{
struct kasan_alloc_meta *alloc_meta;
u8 idx = 0;
alloc_meta = get_alloc_info(cache, object);
#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
idx = alloc_meta->free_track_idx;
alloc_meta->free_pointer_tag[idx] = tag;
alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS;
#endif
set_track(&alloc_meta->free_track[idx], GFP_NOWAIT);
}
void kasan_poison_slab(struct page *page)
{
unsigned long i;
@ -491,7 +473,7 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
KASAN_KMALLOC_REDZONE);
if (cache->flags & SLAB_KASAN)
set_track(&get_alloc_info(cache, object)->alloc_track, flags);
kasan_set_track(&get_alloc_info(cache, object)->alloc_track, flags);
return set_tag(object, tag);
}

22
mm/kasan/generic.c
View File

@ -345,3 +345,25 @@ void kasan_record_aux_stack(void *addr)
alloc_info->aux_stack[1] = alloc_info->aux_stack[0];
alloc_info->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 = get_free_info(cache, object);
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;
return &get_free_info(cache, object)->free_track;
}

1
mm/kasan/generic_report.c
View File

@ -80,6 +80,7 @@ static const char *get_shadow_bug_type(struct kasan_access_info *info)
break;
case KASAN_FREE_PAGE:
case KASAN_KMALLOC_FREE:
case KASAN_KMALLOC_FREETRACK:
bug_type = "use-after-free";
break;
case KASAN_ALLOCA_LEFT:

16
mm/kasan/kasan.h
View File

@ -17,15 +17,17 @@
#define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocations */
#define KASAN_KMALLOC_REDZONE 0xFC /* redzone inside slub object */
#define KASAN_KMALLOC_FREE 0xFB /* object was freed (kmem_cache_free/kfree) */
#define KASAN_KMALLOC_FREETRACK 0xFA /* object was freed and has free track set */
#else
#define KASAN_FREE_PAGE KASAN_TAG_INVALID
#define KASAN_PAGE_REDZONE KASAN_TAG_INVALID
#define KASAN_KMALLOC_REDZONE KASAN_TAG_INVALID
#define KASAN_KMALLOC_FREE KASAN_TAG_INVALID
#define KASAN_KMALLOC_FREETRACK KASAN_TAG_INVALID
#endif
#define KASAN_GLOBAL_REDZONE 0xFA /* redzone for global variable */
#define KASAN_VMALLOC_INVALID 0xF9 /* unallocated space in vmapped page */
#define KASAN_GLOBAL_REDZONE 0xF9 /* redzone for global variable */
#define KASAN_VMALLOC_INVALID 0xF8 /* unallocated space in vmapped page */
/*
* Stack redzone shadow values
@ -110,8 +112,9 @@ struct kasan_alloc_meta {
* The free stack is stored into struct kasan_free_meta.
*/
depot_stack_handle_t aux_stack[2];
#endif
#else
struct kasan_track free_track[KASAN_NR_FREE_STACKS];
#endif
#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
u8 free_pointer_tag[KASAN_NR_FREE_STACKS];
u8 free_track_idx;
@ -126,6 +129,9 @@ struct kasan_free_meta {
* Otherwise it might be used for the allocator freelist.
*/
struct qlist_node quarantine_link;
#ifdef CONFIG_KASAN_GENERIC
struct kasan_track free_track;
#endif
};
struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
@ -167,6 +173,10 @@ void kasan_report_invalid_free(void *object, unsigned long ip);
struct page *kasan_addr_to_page(const void *addr);
depot_stack_handle_t kasan_save_stack(gfp_t flags);
void kasan_set_track(struct kasan_track *track, gfp_t flags);
void kasan_set_free_info(struct kmem_cache *cache, void *object, u8 tag);
struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
void *object, u8 tag);
#if defined(CONFIG_KASAN_GENERIC) && \
(defined(CONFIG_SLAB) || defined(CONFIG_SLUB))

1
mm/kasan/quarantine.c
View File

@ -145,6 +145,7 @@ static void qlink_free(struct qlist_node *qlink, struct kmem_cache *cache)
if (IS_ENABLED(CONFIG_SLAB))
local_irq_save(flags);
*(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREE;
___cache_free(cache, object, _THIS_IP_);
if (IS_ENABLED(CONFIG_SLAB))

26
mm/kasan/report.c
View File

@ -165,26 +165,6 @@ static void describe_object_addr(struct kmem_cache *cache, void *object,
(void *)(object_addr + cache->object_size));
}
static struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
void *object, u8 tag)
{
struct kasan_alloc_meta *alloc_meta;
int i = 0;
alloc_meta = get_alloc_info(cache, object);
#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
for (i = 0; i < KASAN_NR_FREE_STACKS; i++) {
if (alloc_meta->free_pointer_tag[i] == tag)
break;
}
if (i == KASAN_NR_FREE_STACKS)
i = alloc_meta->free_track_idx;
#endif
return &alloc_meta->free_track[i];
}
static void describe_object(struct kmem_cache *cache, void *object,
const void *addr, u8 tag)
{
@ -196,8 +176,10 @@ static void describe_object(struct kmem_cache *cache, void *object,
print_track(&alloc_info->alloc_track, "Allocated");
pr_err("\n");
free_track = kasan_get_free_track(cache, object, tag);
print_track(free_track, "Freed");
pr_err("\n");
if (free_track) {
print_track(free_track, "Freed");
pr_err("\n");
}
#ifdef CONFIG_KASAN_GENERIC
if (alloc_info->aux_stack[0]) {

37
mm/kasan/tags.c
View File

@ -161,3 +161,40 @@ void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size)
kasan_poison_shadow((void *)addr, size, tag);
}
EXPORT_SYMBOL(__hwasan_tag_memory);
void kasan_set_free_info(struct kmem_cache *cache,
void *object, u8 tag)
{
struct kasan_alloc_meta *alloc_meta;
u8 idx = 0;
alloc_meta = get_alloc_info(cache, object);
#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
idx = alloc_meta->free_track_idx;
alloc_meta->free_pointer_tag[idx] = tag;
alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS;
#endif
kasan_set_track(&alloc_meta->free_track[idx], GFP_NOWAIT);
}
struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
void *object, u8 tag)
{
struct kasan_alloc_meta *alloc_meta;
int i = 0;
alloc_meta = get_alloc_info(cache, object);
#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY
for (i = 0; i < KASAN_NR_FREE_STACKS; i++) {
if (alloc_meta->free_pointer_tag[i] == tag)
break;
}
if (i == KASAN_NR_FREE_STACKS)
i = alloc_meta->free_track_idx;
#endif
return &alloc_meta->free_track[i];
}