From: Andrey Ryabinin a.ryabinin@samsung.com
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 (cherry picked from commit 0316bec22ec95ea2faca6406437b0b5950553b7c) Signed-off-by: Alex Shi alex.shi@linaro.org
Conflicts: skip memcg part in mm/slub.c --- include/linux/kasan.h | 27 ++++++++++++++ include/linux/slab.h | 11 ++++-- lib/Kconfig.kasan | 1 + mm/Makefile | 3 ++ mm/kasan/kasan.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++ mm/kasan/kasan.h | 5 +++ mm/kasan/report.c | 21 +++++++++++ mm/slab_common.c | 5 ++- mm/slub.c | 31 ++++++++++++++-- 9 files changed, 197 insertions(+), 5 deletions(-)
diff --git a/include/linux/kasan.h b/include/linux/kasan.h index f00c15c..d5310ee 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -37,6 +37,18 @@ void kasan_unpoison_shadow(const void *address, size_t size); void kasan_alloc_pages(struct page *page, unsigned int order); void kasan_free_pages(struct page *page, unsigned int order);
+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_kmalloc_large(const void *ptr, size_t size); +void kasan_kfree_large(const void *ptr); +void kasan_kmalloc(struct kmem_cache *s, const void *object, size_t size); +void kasan_krealloc(const void *object, size_t new_size); + +void kasan_slab_alloc(struct kmem_cache *s, void *object); +void kasan_slab_free(struct kmem_cache *s, void *object); + #else /* CONFIG_KASAN */
static inline void kasan_unpoison_shadow(const void *address, size_t size) {} @@ -47,6 +59,21 @@ static inline void kasan_disable_current(void) {} static inline void kasan_alloc_pages(struct page *page, unsigned int order) {} static inline void kasan_free_pages(struct page *page, unsigned int order) {}
+static inline void kasan_poison_slab(struct page *page) {} +static inline void kasan_unpoison_object_data(struct kmem_cache *cache, + void *object) {} +static inline void kasan_poison_object_data(struct kmem_cache *cache, + void *object) {} + +static inline void kasan_kmalloc_large(void *ptr, size_t size) {} +static inline void kasan_kfree_large(const void *ptr) {} +static inline void kasan_kmalloc(struct kmem_cache *s, const void *object, + size_t size) {} +static inline void kasan_krealloc(const void *object, size_t new_size) {} + +static inline void kasan_slab_alloc(struct kmem_cache *s, void *object) {} +static inline void kasan_slab_free(struct kmem_cache *s, void *object) {} + #endif /* CONFIG_KASAN */
#endif /* LINUX_KASAN_H */ diff --git a/include/linux/slab.h b/include/linux/slab.h index c265bec..5f97037 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -104,6 +104,7 @@ (unsigned long)ZERO_SIZE_PTR)
#include <linux/kmemleak.h> +#include <linux/kasan.h>
struct mem_cgroup; /* @@ -326,7 +327,10 @@ kmem_cache_alloc_node_trace(struct kmem_cache *s, static __always_inline void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t flags, size_t size) { - return kmem_cache_alloc(s, flags); + void *ret = kmem_cache_alloc(s, flags); + + kasan_kmalloc(s, ret, size); + return ret; }
static __always_inline void * @@ -334,7 +338,10 @@ kmem_cache_alloc_node_trace(struct kmem_cache *s, gfp_t gfpflags, int node, size_t size) { - return kmem_cache_alloc_node(s, gfpflags, node); + void *ret = kmem_cache_alloc_node(s, gfpflags, node); + + kasan_kmalloc(s, ret, size); + return ret; } #endif /* CONFIG_TRACING */
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index 0052b1b..a11ac02 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -5,6 +5,7 @@ if HAVE_ARCH_KASAN
config KASAN bool "KASan: runtime memory debugger" + depends on SLUB_DEBUG help Enables kernel address sanitizer - runtime memory debugger, designed to find out-of-bounds accesses and use-after-free bugs. diff --git a/mm/Makefile b/mm/Makefile index 61b1a43..3614adb 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) := fremap.o 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 @@ void kasan_free_pages(struct page *page, unsigned int order) 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 @@ static void print_error_description(struct kasan_access_info *info)
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 @@ static void print_address_description(struct kasan_access_info *info) 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 dcdab81..9a18f19 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -789,6 +789,7 @@ void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) 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); @@ -963,8 +964,10 @@ static __always_inline void *__do_krealloc(const void *p, size_t new_size, 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 d569522..b8b76d5 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1251,11 +1251,13 @@ 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) { 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 int slab_pre_alloc_hook(struct kmem_cache *s, gfp_t flags) @@ -1273,6 +1275,7 @@ static inline void slab_post_alloc_hook(struct kmem_cache *s, flags &= gfp_allowed_mask; kmemcheck_slab_alloc(s, flags, object, slab_ksize(s)); kmemleak_alloc_recursive(object, s->object_size, 1, s->flags, flags); + kasan_slab_alloc(s, object); }
static inline void slab_free_hook(struct kmem_cache *s, void *x) @@ -1296,6 +1299,8 @@ static inline void slab_free_hook(struct kmem_cache *s, void *x) #endif if (!(s->flags & SLAB_DEBUG_OBJECTS)) debug_check_no_obj_freed(x, s->object_size); + + kasan_slab_free(s, x); }
/* @@ -1390,8 +1395,11 @@ static void setup_object(struct kmem_cache *s, struct page *page, 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) @@ -1421,6 +1429,8 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node) 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)) @@ -2497,6 +2507,7 @@ void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size) { 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); @@ -2523,6 +2534,8 @@ void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
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); @@ -2906,6 +2919,7 @@ static void early_kmem_cache_node_alloc(int node) 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);
@@ -3278,6 +3292,8 @@ void *__kmalloc(size_t size, gfp_t flags)
trace_kmalloc(_RET_IP_, ret, size, s->size, flags);
+ kasan_kmalloc(s, ret, size); + return ret; } EXPORT_SYMBOL(__kmalloc); @@ -3321,12 +3337,14 @@ void *__kmalloc_node(size_t size, gfp_t flags, int node)
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;
@@ -3342,6 +3360,15 @@ size_t ksize(const void *object)
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)