mm: slub: add kernel address sanitizer support for slub allocator
With this patch kasan will be able to catch bugs in memory allocated by
slub. Initially all objects in newly allocated slab page, marked as
redzone. Later, when allocation of slub object happens, requested by
caller number of bytes marked as accessible, and the rest of the object
(including slub's metadata) marked as redzone (inaccessible).
We also mark object as accessible if ksize was called for this object.
There is some places in kernel where ksize function is called to inquire
size of really allocated area. Such callers could validly access whole
allocated memory, so it should be marked as accessible.
Code in slub.c and slab_common.c files could validly access to object's
metadata, so instrumentation for this files are disabled.
Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Signed-off-by: Dmitry Chernenkov <dmitryc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Signed-off-by: Andrey Konovalov <adech.fo@gmail.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/Makefile b/mm/Makefile
index 930b52d..088c68e 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -2,6 +2,9 @@
# Makefile for the linux memory manager.
#
+KASAN_SANITIZE_slab_common.o := n
+KASAN_SANITIZE_slub.o := n
+
mmu-y := nommu.o
mmu-$(CONFIG_MMU) := gup.o highmem.o memory.o mincore.o \
mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index b516eb8..dc83f07 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -31,6 +31,7 @@
#include <linux/kasan.h>
#include "kasan.h"
+#include "../slab.h"
/*
* Poisons the shadow memory for 'size' bytes starting from 'addr'.
@@ -268,6 +269,103 @@
KASAN_FREE_PAGE);
}
+void kasan_poison_slab(struct page *page)
+{
+ kasan_poison_shadow(page_address(page),
+ PAGE_SIZE << compound_order(page),
+ KASAN_KMALLOC_REDZONE);
+}
+
+void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
+{
+ kasan_unpoison_shadow(object, cache->object_size);
+}
+
+void kasan_poison_object_data(struct kmem_cache *cache, void *object)
+{
+ kasan_poison_shadow(object,
+ round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
+ KASAN_KMALLOC_REDZONE);
+}
+
+void kasan_slab_alloc(struct kmem_cache *cache, void *object)
+{
+ kasan_kmalloc(cache, object, cache->object_size);
+}
+
+void kasan_slab_free(struct kmem_cache *cache, void *object)
+{
+ unsigned long size = cache->object_size;
+ unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
+
+ /* RCU slabs could be legally used after free within the RCU period */
+ if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
+ return;
+
+ kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
+}
+
+void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size)
+{
+ unsigned long redzone_start;
+ unsigned long redzone_end;
+
+ if (unlikely(object == NULL))
+ return;
+
+ redzone_start = round_up((unsigned long)(object + size),
+ KASAN_SHADOW_SCALE_SIZE);
+ redzone_end = round_up((unsigned long)object + cache->object_size,
+ KASAN_SHADOW_SCALE_SIZE);
+
+ kasan_unpoison_shadow(object, size);
+ kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
+ KASAN_KMALLOC_REDZONE);
+}
+EXPORT_SYMBOL(kasan_kmalloc);
+
+void kasan_kmalloc_large(const void *ptr, size_t size)
+{
+ struct page *page;
+ unsigned long redzone_start;
+ unsigned long redzone_end;
+
+ if (unlikely(ptr == NULL))
+ return;
+
+ page = virt_to_page(ptr);
+ redzone_start = round_up((unsigned long)(ptr + size),
+ KASAN_SHADOW_SCALE_SIZE);
+ redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
+
+ kasan_unpoison_shadow(ptr, size);
+ kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
+ KASAN_PAGE_REDZONE);
+}
+
+void kasan_krealloc(const void *object, size_t size)
+{
+ struct page *page;
+
+ if (unlikely(object == ZERO_SIZE_PTR))
+ return;
+
+ page = virt_to_head_page(object);
+
+ if (unlikely(!PageSlab(page)))
+ kasan_kmalloc_large(object, size);
+ else
+ kasan_kmalloc(page->slab_cache, object, size);
+}
+
+void kasan_kfree_large(const void *ptr)
+{
+ struct page *page = virt_to_page(ptr);
+
+ kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
+ KASAN_FREE_PAGE);
+}
+
#define DEFINE_ASAN_LOAD_STORE(size) \
void __asan_load##size(unsigned long addr) \
{ \
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index d3c90d5..5b052ab 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -7,6 +7,11 @@
#define KASAN_SHADOW_MASK (KASAN_SHADOW_SCALE_SIZE - 1)
#define KASAN_FREE_PAGE 0xFF /* page was freed */
+#define KASAN_FREE_PAGE 0xFF /* page was freed */
+#define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocations */
+#define KASAN_KMALLOC_REDZONE 0xFC /* redzone inside slub object */
+#define KASAN_KMALLOC_FREE 0xFB /* object was freed (kmem_cache_free/kfree) */
+
struct kasan_access_info {
const void *access_addr;
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index fab8e78..2760edb 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -24,6 +24,7 @@
#include <linux/kasan.h>
#include "kasan.h"
+#include "../slab.h"
/* Shadow layout customization. */
#define SHADOW_BYTES_PER_BLOCK 1
@@ -55,8 +56,11 @@
switch (shadow_val) {
case KASAN_FREE_PAGE:
+ case KASAN_KMALLOC_FREE:
bug_type = "use after free";
break;
+ case KASAN_PAGE_REDZONE:
+ case KASAN_KMALLOC_REDZONE:
case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
bug_type = "out of bounds access";
break;
@@ -77,6 +81,23 @@
if ((addr >= (void *)PAGE_OFFSET) &&
(addr < high_memory)) {
struct page *page = virt_to_head_page(addr);
+
+ if (PageSlab(page)) {
+ void *object;
+ struct kmem_cache *cache = page->slab_cache;
+ void *last_object;
+
+ object = virt_to_obj(cache, page_address(page), addr);
+ last_object = page_address(page) +
+ page->objects * cache->size;
+
+ if (unlikely(object > last_object))
+ object = last_object; /* we hit into padding */
+
+ object_err(cache, page, object,
+ "kasan: bad access detected");
+ return;
+ }
dump_page(page, "kasan: bad access detected");
}
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 429a450..999bb34 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -898,6 +898,7 @@
page = alloc_kmem_pages(flags, order);
ret = page ? page_address(page) : NULL;
kmemleak_alloc(ret, size, 1, flags);
+ kasan_kmalloc_large(ret, size);
return ret;
}
EXPORT_SYMBOL(kmalloc_order);
@@ -1077,8 +1078,10 @@
if (p)
ks = ksize(p);
- if (ks >= new_size)
+ if (ks >= new_size) {
+ kasan_krealloc((void *)p, new_size);
return (void *)p;
+ }
ret = kmalloc_track_caller(new_size, flags);
if (ret && p)
diff --git a/mm/slub.c b/mm/slub.c
index 37555ad..6832c4e 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1251,11 +1251,13 @@
static inline void kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags)
{
kmemleak_alloc(ptr, size, 1, flags);
+ kasan_kmalloc_large(ptr, size);
}
static inline void kfree_hook(const void *x)
{
kmemleak_free(x);
+ kasan_kfree_large(x);
}
static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
@@ -1278,6 +1280,7 @@
kmemcheck_slab_alloc(s, flags, object, slab_ksize(s));
kmemleak_alloc_recursive(object, s->object_size, 1, s->flags, flags);
memcg_kmem_put_cache(s);
+ kasan_slab_alloc(s, object);
}
static inline void slab_free_hook(struct kmem_cache *s, void *x)
@@ -1301,6 +1304,8 @@
#endif
if (!(s->flags & SLAB_DEBUG_OBJECTS))
debug_check_no_obj_freed(x, s->object_size);
+
+ kasan_slab_free(s, x);
}
/*
@@ -1395,8 +1400,11 @@
void *object)
{
setup_object_debug(s, page, object);
- if (unlikely(s->ctor))
+ if (unlikely(s->ctor)) {
+ kasan_unpoison_object_data(s, object);
s->ctor(object);
+ kasan_poison_object_data(s, object);
+ }
}
static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
@@ -1429,6 +1437,8 @@
if (unlikely(s->flags & SLAB_POISON))
memset(start, POISON_INUSE, PAGE_SIZE << order);
+ kasan_poison_slab(page);
+
for_each_object_idx(p, idx, s, start, page->objects) {
setup_object(s, page, p);
if (likely(idx < page->objects))
@@ -2522,6 +2532,7 @@
{
void *ret = slab_alloc(s, gfpflags, _RET_IP_);
trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags);
+ kasan_kmalloc(s, ret, size);
return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc_trace);
@@ -2548,6 +2559,8 @@
trace_kmalloc_node(_RET_IP_, ret,
size, s->size, gfpflags, node);
+
+ kasan_kmalloc(s, ret, size);
return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
@@ -2933,6 +2946,7 @@
init_object(kmem_cache_node, n, SLUB_RED_ACTIVE);
init_tracking(kmem_cache_node, n);
#endif
+ kasan_kmalloc(kmem_cache_node, n, sizeof(struct kmem_cache_node));
init_kmem_cache_node(n);
inc_slabs_node(kmem_cache_node, node, page->objects);
@@ -3305,6 +3319,8 @@
trace_kmalloc(_RET_IP_, ret, size, s->size, flags);
+ kasan_kmalloc(s, ret, size);
+
return ret;
}
EXPORT_SYMBOL(__kmalloc);
@@ -3348,12 +3364,14 @@
trace_kmalloc_node(_RET_IP_, ret, size, s->size, flags, node);
+ kasan_kmalloc(s, ret, size);
+
return ret;
}
EXPORT_SYMBOL(__kmalloc_node);
#endif
-size_t ksize(const void *object)
+static size_t __ksize(const void *object)
{
struct page *page;
@@ -3369,6 +3387,15 @@
return slab_ksize(page->slab_cache);
}
+
+size_t ksize(const void *object)
+{
+ size_t size = __ksize(object);
+ /* We assume that ksize callers could use whole allocated area,
+ so we need unpoison this area. */
+ kasan_krealloc(object, size);
+ return size;
+}
EXPORT_SYMBOL(ksize);
void kfree(const void *x)