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Subject[PATCH 2/5] kasan, kmemleak: pass tagged pointers to kmemleak
Date
Right now we call kmemleak hooks before assigning tags to pointers in
KASAN hooks. As a result, when an objects gets allocated, kmemleak sees
a differently tagged pointer, compared to the one it sees when the object
gets freed. Fix it by calling KASAN hooks before kmemleak's ones.

Reported-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
mm/slab.h | 6 ++----
mm/slab_common.c | 2 +-
mm/slub.c | 3 ++-
3 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/mm/slab.h b/mm/slab.h
index 4190c24ef0e9..638ea1b25d39 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -437,11 +437,9 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags,

flags &= gfp_allowed_mask;
for (i = 0; i < size; i++) {
- void *object = p[i];
-
- kmemleak_alloc_recursive(object, s->object_size, 1,
+ p[i] = kasan_slab_alloc(s, p[i], flags);
+ kmemleak_alloc_recursive(p[i], s->object_size, 1,
s->flags, flags);
- p[i] = kasan_slab_alloc(s, object, flags);
}

if (memcg_kmem_enabled())
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 81732d05e74a..fe524c8d0246 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1228,8 +1228,8 @@ void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
flags |= __GFP_COMP;
page = alloc_pages(flags, order);
ret = page ? page_address(page) : NULL;
- kmemleak_alloc(ret, size, 1, flags);
ret = kasan_kmalloc_large(ret, size, flags);
+ kmemleak_alloc(ret, size, 1, flags);
return ret;
}
EXPORT_SYMBOL(kmalloc_order);
diff --git a/mm/slub.c b/mm/slub.c
index 1e3d0ec4e200..4a3d7686902f 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1374,8 +1374,9 @@ static inline void dec_slabs_node(struct kmem_cache *s, int node,
*/
static inline void *kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags)
{
+ ptr = kasan_kmalloc_large(ptr, size, flags);
kmemleak_alloc(ptr, size, 1, flags);
- return kasan_kmalloc_large(ptr, size, flags);
+ return ptr;
}

static __always_inline void kfree_hook(void *x)
--
2.20.1.791.gb4d0f1c61a-goog
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