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Subject[PATCH 2/5] kasan: don't use __builtin_return_address(1)
Date
__builtin_return_address(1) is unreliable without frame pointers.
With defconfig on kmalloc_pagealloc_invalid_free test I am getting:

BUG: KASAN: double-free or invalid-free in (null)

Pass caller PC from callers explicitly.

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Cc: kasan-dev@googlegroups.com
---
include/linux/kasan.h | 9 +++++----
mm/kasan/kasan.c | 8 ++++----
mm/kasan/kasan.h | 2 +-
mm/kasan/report.c | 4 ++--
mm/slab.c | 6 +++---
mm/slub.c | 8 ++++----
6 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index fc9e642533f8..f0d13c30acc6 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -56,14 +56,14 @@ 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(void *ptr);
+void kasan_kfree_large(void *ptr, unsigned long ip);
void kasan_poison_kfree(void *ptr);
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 kasan_slab_alloc(struct kmem_cache *s, void *object, gfp_t flags);
-bool kasan_slab_free(struct kmem_cache *s, void *object);
+bool kasan_slab_free(struct kmem_cache *s, void *object, unsigned long ip);

struct kasan_cache {
int alloc_meta_offset;
@@ -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(void *ptr) {}
+static inline void kasan_kfree_large(void *ptr, unsigned long ip) {}
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) {}
@@ -117,7 +117,8 @@ static inline void kasan_krealloc(const void *object, size_t new_size,

static inline void kasan_slab_alloc(struct kmem_cache *s, void *object,
gfp_t flags) {}
-static inline bool kasan_slab_free(struct kmem_cache *s, void *object)
+static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
+ unsigned long ip)
{
return false;
}
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index ecb64fda79e6..32f555ded938 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -501,7 +501,7 @@ static void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
}

-bool kasan_slab_free(struct kmem_cache *cache, void *object)
+bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
{
s8 shadow_byte;

@@ -511,7 +511,7 @@ bool kasan_slab_free(struct kmem_cache *cache, void *object)

shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
if (shadow_byte < 0 || shadow_byte >= KASAN_SHADOW_SCALE_SIZE) {
- kasan_report_invalid_free(object, __builtin_return_address(1));
+ kasan_report_invalid_free(object, ip);
return true;
}

@@ -601,10 +601,10 @@ void kasan_poison_kfree(void *ptr)
kasan_poison_slab_free(page->slab_cache, ptr);
}

-void kasan_kfree_large(void *ptr)
+void kasan_kfree_large(void *ptr, unsigned long ip)
{
if (ptr != page_address(virt_to_head_page(ptr)))
- kasan_report_invalid_free(ptr, __builtin_return_address(1));
+ kasan_report_invalid_free(ptr, ip);
/* The object will be poisoned by page_alloc. */
}

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 57f517d1dfce..2792de927fcd 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -107,7 +107,7 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)

void kasan_report(unsigned long addr, size_t size,
bool is_write, unsigned long ip);
-void kasan_report_invalid_free(void *object, void *ip);
+void kasan_report_invalid_free(void *object, unsigned long ip);

#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB)
void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache);
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 55916ad21722..75206991ece0 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -326,12 +326,12 @@ static void print_shadow_for_address(const void *addr)
}
}

-void kasan_report_invalid_free(void *object, void *ip)
+void kasan_report_invalid_free(void *object, unsigned long ip)
{
unsigned long flags;

kasan_start_report(&flags);
- pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", ip);
+ pr_err("BUG: KASAN: double-free or invalid-free in %pS\n", (void *)ip);
pr_err("\n");
print_address_description(object);
pr_err("\n");
diff --git a/mm/slab.c b/mm/slab.c
index 6bc4e609e24b..d074fd0790f4 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3478,11 +3478,11 @@ static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac)
* Release an obj back to its cache. If the obj has a constructed state, it must
* be in this state _before_ it is released. Called with disabled ints.
*/
-static inline void __cache_free(struct kmem_cache *cachep, void *objp,
- unsigned long caller)
+static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp,
+ unsigned long caller)
{
/* Put the object into the quarantine, don't touch it for now. */
- if (kasan_slab_free(cachep, objp))
+ if (kasan_slab_free(cachep, objp, _RET_IP_))
return;

___cache_free(cachep, objp, caller);
diff --git a/mm/slub.c b/mm/slub.c
index 67c8cee43cf6..b1e41572c6cb 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1354,13 +1354,13 @@ static inline void kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags)
kasan_kmalloc_large(ptr, size, flags);
}

-static inline void kfree_hook(void *x)
+static __always_inline void kfree_hook(void *x)
{
kmemleak_free(x);
- kasan_kfree_large(x);
+ kasan_kfree_large(x, _RET_IP_);
}

-static inline void *slab_free_hook(struct kmem_cache *s, void *x)
+static __always_inline void *slab_free_hook(struct kmem_cache *s, void *x)
{
void *freeptr;

@@ -1388,7 +1388,7 @@ static inline void *slab_free_hook(struct kmem_cache *s, void *x)
* kasan_slab_free() may put x into memory quarantine, delaying its
* reuse. In this case the object's freelist pointer is changed.
*/
- kasan_slab_free(s, x);
+ kasan_slab_free(s, x, _RET_IP_);
return freeptr;
}

--
2.15.1.620.gb9897f4670-goog
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