[PATCH v13 22/25] kasan: add __must_check annotations to kasan hooks

[Andrey Konovalov <andreyknvl@xxxxxxxxxx>]

This patch adds __must_check annotations to kasan hooks that return a
pointer to make sure that a tagged pointer always gets propagated.

Suggested-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
 include/linux/kasan.h | 16 ++++++++++------
 mm/kasan/common.c     | 15 +++++++++------
 2 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 8da7b7a4397a..b40ea104dd36 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -49,16 +49,20 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
 void kasan_poison_slab(struct page *page);
 void kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
 void kasan_poison_object_data(struct kmem_cache *cache, void *object);
-void *kasan_init_slab_obj(struct kmem_cache *cache, const void *object);
+void * __must_check 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 * __must_check 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, 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);
+void * __must_check kasan_kmalloc(struct kmem_cache *s, const void *object,
+					size_t size, gfp_t flags);
+void * __must_check kasan_krealloc(const void *object, size_t new_size,
+					gfp_t flags);
 
-void *kasan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags);
+void * __must_check kasan_slab_alloc(struct kmem_cache *s, void *object,
+					gfp_t flags);
 bool kasan_slab_free(struct kmem_cache *s, void *object, unsigned long ip);
 
 struct kasan_cache {
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 195ca385cf7a..1144e741feb6 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -373,7 +373,8 @@ static u8 assign_tag(struct kmem_cache *cache, const void *object, bool new)
 #endif
 }
 
-void *kasan_init_slab_obj(struct kmem_cache *cache, const void *object)
+void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
+						const void *object)
 {
 	struct kasan_alloc_meta *alloc_info;
 
@@ -389,7 +390,8 @@ void *kasan_init_slab_obj(struct kmem_cache *cache, const void *object)
 	return (void *)object;
 }
 
-void *kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags)
+void * __must_check kasan_slab_alloc(struct kmem_cache *cache, void *object,
+					gfp_t flags)
 {
 	return kasan_kmalloc(cache, object, cache->object_size, flags);
 }
@@ -449,8 +451,8 @@ bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
 	return __kasan_slab_free(cache, object, ip, true);
 }
 
-void *kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
-		   gfp_t flags)
+void * __must_check kasan_kmalloc(struct kmem_cache *cache, const void *object,
+					size_t size, gfp_t flags)
 {
 	unsigned long redzone_start;
 	unsigned long redzone_end;
@@ -482,7 +484,8 @@ void *kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
 }
 EXPORT_SYMBOL(kasan_kmalloc);
 
-void *kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
+void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
+						gfp_t flags)
 {
 	struct page *page;
 	unsigned long redzone_start;
@@ -506,7 +509,7 @@ void *kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
 	return (void *)ptr;
 }
 
-void *kasan_krealloc(const void *object, size_t size, gfp_t flags)
+void * __must_check kasan_krealloc(const void *object, size_t size, gfp_t flags)
 {
 	struct page *page;
 
-- 
2.20.0.rc1.387.gf8505762e3-goog