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authorDmitry Vyukov <dvyukov@google.com>2018-02-06 15:36:30 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-06 18:32:43 -0800
commit6860f6340c0918cddcd3c9fcf8c36401c8184268 (patch)
tree59b652f61341d35394d745a3010bb437a54d6421
parentee3ce779b58c31acacdfab0ad6c86d428ba2c2e3 (diff)
downloadlinux-6860f6340c0918cddcd3c9fcf8c36401c8184268.tar.bz2
kasan: detect invalid frees for large mempool objects
Detect frees of pointers into middle of mempool objects. I did a one-off test, but it turned out to be very tricky, so I reverted it. First, mempool does not call kasan_poison_kfree() unless allocation function fails. I stubbed an allocation function to fail on second and subsequent allocations. But then mempool stopped to call kasan_poison_kfree() at all, because it does it only when allocation function is mempool_kmalloc(). We could support this special failing test allocation function in mempool, but it also can't live with kasan tests, because these are in a module. Link: http://lkml.kernel.org/r/bf7a7d035d7a5ed62d2dd0e3d2e8a4fcdf456aa7.1514378558.git.dvyukov@google.com Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>a Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--include/linux/kasan.h4
-rw-r--r--mm/kasan/kasan.c11
-rw-r--r--mm/mempool.c6
3 files changed, 13 insertions, 8 deletions
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index f0d13c30acc6..fc45f8952d1e 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -57,7 +57,7 @@ void kasan_init_slab_obj(struct kmem_cache *cache, const void *object);
void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags);
void kasan_kfree_large(void *ptr, unsigned long ip);
-void kasan_poison_kfree(void *ptr);
+void kasan_poison_kfree(void *ptr, unsigned long ip);
void kasan_kmalloc(struct kmem_cache *s, const void *object, size_t size,
gfp_t flags);
void kasan_krealloc(const void *object, size_t new_size, gfp_t flags);
@@ -109,7 +109,7 @@ static inline void kasan_init_slab_obj(struct kmem_cache *cache,
static inline void kasan_kmalloc_large(void *ptr, size_t size, gfp_t flags) {}
static inline void kasan_kfree_large(void *ptr, unsigned long ip) {}
-static inline void kasan_poison_kfree(void *ptr) {}
+static inline void kasan_poison_kfree(void *ptr, unsigned long ip) {}
static inline void kasan_kmalloc(struct kmem_cache *s, const void *object,
size_t size, gfp_t flags) {}
static inline void kasan_krealloc(const void *object, size_t new_size,
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 32f555ded938..77c103748728 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -588,17 +588,22 @@ void kasan_krealloc(const void *object, size_t size, gfp_t flags)
kasan_kmalloc(page->slab_cache, object, size, flags);
}
-void kasan_poison_kfree(void *ptr)
+void kasan_poison_kfree(void *ptr, unsigned long ip)
{
struct page *page;
page = virt_to_head_page(ptr);
- if (unlikely(!PageSlab(page)))
+ if (unlikely(!PageSlab(page))) {
+ if (ptr != page_address(page)) {
+ kasan_report_invalid_free(ptr, ip);
+ return;
+ }
kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
KASAN_FREE_PAGE);
- else
+ } else {
kasan_poison_slab_free(page->slab_cache, ptr);
+ }
}
void kasan_kfree_large(void *ptr, unsigned long ip)
diff --git a/mm/mempool.c b/mm/mempool.c
index 7d8c5a0010a2..5c9dce34719b 100644
--- a/mm/mempool.c
+++ b/mm/mempool.c
@@ -103,10 +103,10 @@ static inline void poison_element(mempool_t *pool, void *element)
}
#endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
-static void kasan_poison_element(mempool_t *pool, void *element)
+static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
{
if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
- kasan_poison_kfree(element);
+ kasan_poison_kfree(element, _RET_IP_);
if (pool->alloc == mempool_alloc_pages)
kasan_free_pages(element, (unsigned long)pool->pool_data);
}
@@ -119,7 +119,7 @@ static void kasan_unpoison_element(mempool_t *pool, void *element, gfp_t flags)
kasan_alloc_pages(element, (unsigned long)pool->pool_data);
}
-static void add_element(mempool_t *pool, void *element)
+static __always_inline void add_element(mempool_t *pool, void *element)
{
BUG_ON(pool->curr_nr >= pool->min_nr);
poison_element(pool, element);