kasan: detect invalid frees for large objects

Patch series "kasan: detect invalid frees".

KASAN detects double-frees, but does not detect invalid-frees (when a
pointer into a middle of heap object is passed to free).  We recently had
a very unpleasant case in crypto code which freed an inner object inside
of a heap allocation.  This left unnoticed during free, but totally
corrupted heap and later lead to a bunch of random crashes all over kernel
code.

Detect invalid frees.

This patch (of 5):

Detect frees of pointers into middle of large heap objects.

I dropped const from kasan_kfree_large() because it starts propagating
through a bunch of functions in kasan_report.c, slab/slub nearest_obj(),
all of their local variables, fixup_red_left(), etc.

Link: http://lkml.kernel.org/r/1b45b4fe1d20fc0de1329aab674c1dd973fee723.1514378558.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>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index e3eb834c9a35..fc9e642533f8 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -56,7 +56,7 @@ void kasan_poison_object_data(struct kmem_cache *cache, void *object);
 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(const void *ptr);
+void kasan_kfree_large(void *ptr);
 void kasan_poison_kfree(void *ptr);
 void kasan_kmalloc(struct kmem_cache *s, const void *object, size_t size,
 		  gfp_t flags);
@@ -108,7 +108,7 @@ static inline void kasan_init_slab_obj(struct kmem_cache *cache,
 				const void *object) {}
 
 static inline void kasan_kmalloc_large(void *ptr, size_t size, gfp_t flags) {}
-static inline void kasan_kfree_large(const void *ptr) {}
+static inline void kasan_kfree_large(void *ptr) {}
 static inline void kasan_poison_kfree(void *ptr) {}
 static inline void kasan_kmalloc(struct kmem_cache *s, const void *object,
 				size_t size, gfp_t flags) {}