linux-kernel - [PATCH 2/5] kasan, kmemleak: pass tagged pointers to kmemleak

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Message-Id: <cd825aa4897b0fc37d3316838993881daccbe9f5.1549921721.git.andreyknvl@google.com>
Date:   Mon, 11 Feb 2019 22:59:51 +0100
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Qian Cai <cai@....pw>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Kostya Serebryany <kcc@...gle.com>,
        Evgeniy Stepanov <eugenis@...gle.com>,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH 2/5] kasan, kmemleak: pass tagged pointers to kmemleak

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@....pw>
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.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