12 files changed, 266 insertions, 22 deletions

diff --git a/Documentation/kasan.txt b/Documentation/kasan.txt
index aa1e0c91e368..7dd95b35cd7c 100644
--- a/Documentation/kasan.txt
+++ b/Documentation/kasan.txt
@@ -12,8 +12,7 @@ KASAN uses compile-time instrumentation for checking every memory access,
 therefore you will need a GCC version 4.9.2 or later. GCC 5.0 or later is
 required for detection of out-of-bounds accesses to stack or global variables.
 
-Currently KASAN is supported only for x86_64 architecture and requires the
-kernel to be built with the SLUB allocator.
+Currently KASAN is supported only for x86_64 architecture.
 
 1. Usage
 ========
@@ -27,7 +26,7 @@ inline are compiler instrumentation types. The former produces smaller binary
 the latter is 1.1 - 2 times faster. Inline instrumentation requires a GCC
 version 5.0 or later.
 
-Currently KASAN works only with the SLUB memory allocator.
+KASAN works with both SLUB and SLAB memory allocators.
 For better bug detection and nicer reporting, enable CONFIG_STACKTRACE.
 
 To disable instrumentation for specific files or directories, add a line
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 0fdc798e3ff7..839f2007a0f9 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -48,6 +48,9 @@ void kasan_unpoison_task_stack(struct task_struct *task);
 void kasan_alloc_pages(struct page *page, unsigned int order);
 void kasan_free_pages(struct page *page, unsigned int order);
 
+void kasan_cache_create(struct kmem_cache *cache, size_t *size,
+                        unsigned long *flags);
+
 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);
@@ -61,6 +64,11 @@ 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);
 
+struct kasan_cache {
+        int alloc_meta_offset;
+        int free_meta_offset;
+};
+
 int kasan_module_alloc(void *addr, size_t size);
 void kasan_free_shadow(const struct vm_struct *vm);
 
@@ -76,6 +84,10 @@ 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_cache_create(struct kmem_cache *cache,
+                                      size_t *size,
+                                      unsigned long *flags) {}
+
 static inline void kasan_poison_slab(struct page *page) {}
 static inline void kasan_unpoison_object_data(struct kmem_cache *cache,
                                         void *object) {}
diff --git a/include/linux/slab.h b/include/linux/slab.h
index e4b568738ca3..aa61595a1482 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -92,6 +92,12 @@
 # define SLAB_ACCOUNT           0x00000000UL
 #endif
 
+#ifdef CONFIG_KASAN
+#define SLAB_KASAN              0x08000000UL
+#else
+#define SLAB_KASAN              0x00000000UL
+#endif
+
 /* The following flags affect the page allocator grouping pages by mobility */
 #define SLAB_RECLAIM_ACCOUNT    0x00020000UL            /* Objects are reclaimable */
 #define SLAB_TEMPORARY          SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index e878ba35ae91..9edbbf352340 100644
--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h
@@ -76,8 +76,22 @@ struct kmem_cache {
 #ifdef CONFIG_MEMCG
         struct memcg_cache_params memcg_params;
 #endif
+#ifdef CONFIG_KASAN
+        struct kasan_cache kasan_info;
+#endif
 
         struct kmem_cache_node *node[MAX_NUMNODES];
 };
 
+static inline void *nearest_obj(struct kmem_cache *cache, struct page *page,
+                                void *x) {
+        void *object = x - (x - page->s_mem) % cache->size;
+        void *last_object = page->s_mem + (cache->num - 1) * cache->size;
+
+        if (unlikely(object > last_object))
+                return last_object;
+        else
+                return object;
+}
+
 #endif  /* _LINUX_SLAB_DEF_H */
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index ac5143f95ee6..665cd0cd18b8 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -130,4 +130,15 @@ static inline void *virt_to_obj(struct kmem_cache *s,
 void object_err(struct kmem_cache *s, struct page *page,
                 u8 *object, char *reason);
 
+static inline void *nearest_obj(struct kmem_cache *cache, struct page *page,
+                                void *x) {
+        void *object = x - (x - page_address(page)) % cache->size;
+        void *last_object = page_address(page) +
+                (page->objects - 1) * cache->size;
+        if (unlikely(object > last_object))
+                return last_object;
+        else
+                return object;
+}
+
 #endif /* _LINUX_SLUB_DEF_H */
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 0fee5acd5aa0..0e4d2b3b0aee 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -5,7 +5,7 @@ if HAVE_ARCH_KASAN
 
 config KASAN
         bool "KASan: runtime memory debugger"
-        depends on SLUB_DEBUG
+        depends on SLUB_DEBUG || (SLAB && !DEBUG_SLAB)
         select CONSTRUCTORS
         help
           Enables kernel address sanitizer - runtime memory debugger,
@@ -16,6 +16,8 @@ config KASAN
           This feature consumes about 1/8 of available memory and brings about
           ~x3 performance slowdown.
           For better error detection enable CONFIG_STACKTRACE.
+          Currently CONFIG_KASAN doesn't work with CONFIG_DEBUG_SLAB
+          (the resulting kernel does not boot).
 
 choice
         prompt "Instrumentation type"
diff --git a/mm/Makefile b/mm/Makefile
index f5e797cbd128..deb467edca2d 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -3,6 +3,7 @@
 #
 
 KASAN_SANITIZE_slab_common.o := n
+KASAN_SANITIZE_slab.o := n
 KASAN_SANITIZE_slub.o := n
 
 # These files are disabled because they produce non-interesting and/or
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 1ad20ade8c91..7c82509ef169 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -334,6 +334,59 @@ void kasan_free_pages(struct page *page, unsigned int order)
                                 KASAN_FREE_PAGE);
 }
 
+#ifdef CONFIG_SLAB
+/*
+ * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
+ * For larger allocations larger redzones are used.
+ */
+static size_t optimal_redzone(size_t object_size)
+{
+        int rz =
+                object_size <= 64        - 16   ? 16 :
+                object_size <= 128       - 32   ? 32 :
+                object_size <= 512       - 64   ? 64 :
+                object_size <= 4096      - 128  ? 128 :
+                object_size <= (1 << 14) - 256  ? 256 :
+                object_size <= (1 << 15) - 512  ? 512 :
+                object_size <= (1 << 16) - 1024 ? 1024 : 2048;
+        return rz;
+}
+
+void kasan_cache_create(struct kmem_cache *cache, size_t *size,
+                        unsigned long *flags)
+{
+        int redzone_adjust;
+        /* Make sure the adjusted size is still less than
+         * KMALLOC_MAX_CACHE_SIZE.
+         * TODO: this check is only useful for SLAB, but not SLUB. We'll need
+         * to skip it for SLUB when it starts using kasan_cache_create().
+         */
+        if (*size > KMALLOC_MAX_CACHE_SIZE -
+            sizeof(struct kasan_alloc_meta) -
+            sizeof(struct kasan_free_meta))
+                return;
+        *flags |= SLAB_KASAN;
+        /* Add alloc meta. */
+        cache->kasan_info.alloc_meta_offset = *size;
+        *size += sizeof(struct kasan_alloc_meta);
+
+        /* Add free meta. */
+        if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor ||
+            cache->object_size < sizeof(struct kasan_free_meta)) {
+                cache->kasan_info.free_meta_offset = *size;
+                *size += sizeof(struct kasan_free_meta);
+        }
+        redzone_adjust = optimal_redzone(cache->object_size) -
+                (*size - cache->object_size);
+        if (redzone_adjust > 0)
+                *size += redzone_adjust;
+        *size = min(KMALLOC_MAX_CACHE_SIZE,
+                    max(*size,
+                        cache->object_size +
+                        optimal_redzone(cache->object_size)));
+}
+#endif
+
 void kasan_poison_slab(struct page *page)
 {
         kasan_poison_shadow(page_address(page),
@@ -351,8 +404,36 @@ 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);
+#ifdef CONFIG_SLAB
+        if (cache->flags & SLAB_KASAN) {
+                struct kasan_alloc_meta *alloc_info =
+                        get_alloc_info(cache, object);
+                alloc_info->state = KASAN_STATE_INIT;
+        }
+#endif
+}
+
+static inline void set_track(struct kasan_track *track)
+{
+        track->cpu = raw_smp_processor_id();
+        track->pid = current->pid;
+        track->when = jiffies;
 }
 
+#ifdef CONFIG_SLAB
+struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
+                                        const void *object)
+{
+        return (void *)object + cache->kasan_info.alloc_meta_offset;
+}
+
+struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
+                                      const void *object)
+{
+        return (void *)object + cache->kasan_info.free_meta_offset;
+}
+#endif
+
 void kasan_slab_alloc(struct kmem_cache *cache, void *object)
 {
         kasan_kmalloc(cache, object, cache->object_size);
@@ -367,6 +448,17 @@ void kasan_slab_free(struct kmem_cache *cache, void *object)
         if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
                 return;
 
+#ifdef CONFIG_SLAB
+        if (cache->flags & SLAB_KASAN) {
+                struct kasan_free_meta *free_info =
+                        get_free_info(cache, object);
+                struct kasan_alloc_meta *alloc_info =
+                        get_alloc_info(cache, object);
+                alloc_info->state = KASAN_STATE_FREE;
+                set_track(&free_info->track);
+        }
+#endif
+
         kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
 }
 
@@ -386,6 +478,16 @@ void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size)
         kasan_unpoison_shadow(object, size);
         kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
                 KASAN_KMALLOC_REDZONE);
+#ifdef CONFIG_SLAB
+        if (cache->flags & SLAB_KASAN) {
+                struct kasan_alloc_meta *alloc_info =
+                        get_alloc_info(cache, object);
+
+                alloc_info->state = KASAN_STATE_ALLOC;
+                alloc_info->alloc_size = size;
+                set_track(&alloc_info->track);
+        }
+#endif
 }
 EXPORT_SYMBOL(kasan_kmalloc);
 
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 4f6c62e5c21e..7b9e4ab9b66b 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -54,6 +54,40 @@ struct kasan_global {
 #endif
 };
 
+/**
+ * Structures to keep alloc and free tracks *
+ */
+
+enum kasan_state {
+        KASAN_STATE_INIT,
+        KASAN_STATE_ALLOC,
+        KASAN_STATE_FREE
+};
+
+struct kasan_track {
+        u64 cpu : 6;                    /* for NR_CPUS = 64 */
+        u64 pid : 16;                   /* 65536 processes */
+        u64 when : 42;                  /* ~140 years */
+};
+
+struct kasan_alloc_meta {
+        u32 state : 2;  /* enum kasan_state */
+        u32 alloc_size : 30;
+        struct kasan_track track;
+};
+
+struct kasan_free_meta {
+        /* Allocator freelist pointer, unused by KASAN. */
+        void **freelist;
+        struct kasan_track track;
+};
+
+struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
+                                        const void *object);
+struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
+                                        const void *object);
+
+
 static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
 {
         return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 745aa8f36028..3e3385cc97ac 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -115,6 +115,46 @@ static inline bool init_task_stack_addr(const void *addr)
                         sizeof(init_thread_union.stack));
 }
 
+#ifdef CONFIG_SLAB
+static void print_track(struct kasan_track *track)
+{
+        pr_err("PID = %u, CPU = %u, timestamp = %lu\n", track->pid,
+               track->cpu, (unsigned long)track->when);
+}
+
+static void object_err(struct kmem_cache *cache, struct page *page,
+                        void *object, char *unused_reason)
+{
+        struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
+        struct kasan_free_meta *free_info;
+
+        dump_stack();
+        pr_err("Object at %p, in cache %s\n", object, cache->name);
+        if (!(cache->flags & SLAB_KASAN))
+                return;
+        switch (alloc_info->state) {
+        case KASAN_STATE_INIT:
+                pr_err("Object not allocated yet\n");
+                break;
+        case KASAN_STATE_ALLOC:
+                pr_err("Object allocated with size %u bytes.\n",
+                       alloc_info->alloc_size);
+                pr_err("Allocation:\n");
+                print_track(&alloc_info->track);
+                break;
+        case KASAN_STATE_FREE:
+                pr_err("Object freed, allocated with size %u bytes\n",
+                       alloc_info->alloc_size);
+                free_info = get_free_info(cache, object);
+                pr_err("Allocation:\n");
+                print_track(&alloc_info->track);
+                pr_err("Deallocation:\n");
+                print_track(&free_info->track);
+                break;
+        }
+}
+#endif
+
 static void print_address_description(struct kasan_access_info *info)
 {
         const void *addr = info->access_addr;
@@ -126,17 +166,10 @@ static void print_address_description(struct kasan_access_info *info)
                 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 = nearest_obj(cache, page,
+                                                (void *)info->access_addr);
                         object_err(cache, page, object,
-                                "kasan: bad access detected");
+                                        "kasan: bad access detected");
                         return;
                 }
                 dump_page(page, "kasan: bad access detected");
@@ -146,7 +179,6 @@ static void print_address_description(struct kasan_access_info *info)
                 if (!init_task_stack_addr(addr))
                         pr_err("Address belongs to variable %pS\n", addr);
         }
-
         dump_stack();
 }
 
diff --git a/mm/slab.c b/mm/slab.c
index e719a5cb3396..7515578471d8 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2086,6 +2086,8 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
         }
 #endif
 
+        kasan_cache_create(cachep, &size, &flags);
+
         size = ALIGN(size, cachep->align);
         /*
          * We should restrict the number of objects in a slab to implement
@@ -2387,8 +2389,13 @@ static void cache_init_objs_debug(struct kmem_cache *cachep, struct page *page)
                  * cache which they are a constructor for.  Otherwise, deadlock.
                  * They must also be threaded.
                  */
-                if (cachep->ctor && !(cachep->flags & SLAB_POISON))
+                if (cachep->ctor && !(cachep->flags & SLAB_POISON)) {
+                        kasan_unpoison_object_data(cachep,
+                                                   objp + obj_offset(cachep));
                         cachep->ctor(objp + obj_offset(cachep));
+                        kasan_poison_object_data(
+                                cachep, objp + obj_offset(cachep));
+                }
 
                 if (cachep->flags & SLAB_RED_ZONE) {
                         if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
@@ -2409,6 +2416,7 @@ static void cache_init_objs(struct kmem_cache *cachep,
                             struct page *page)
 {
         int i;
+        void *objp;
 
         cache_init_objs_debug(cachep, page);
 
@@ -2419,8 +2427,12 @@ static void cache_init_objs(struct kmem_cache *cachep,
 
         for (i = 0; i < cachep->num; i++) {
                 /* constructor could break poison info */
-                if (DEBUG == 0 && cachep->ctor)
-                        cachep->ctor(index_to_obj(cachep, page, i));
+                if (DEBUG == 0 && cachep->ctor) {
+                        objp = index_to_obj(cachep, page, i);
+                        kasan_unpoison_object_data(cachep, objp);
+                        cachep->ctor(objp);
+                        kasan_poison_object_data(cachep, objp);
+                }
 
                 set_free_obj(page, i, i);
         }
@@ -2550,6 +2562,7 @@ static int cache_grow(struct kmem_cache *cachep,
 
         slab_map_pages(cachep, page, freelist);
 
+        kasan_poison_slab(page);
         cache_init_objs(cachep, page);
 
         if (gfpflags_allow_blocking(local_flags))
@@ -3316,6 +3329,8 @@ static inline void __cache_free(struct kmem_cache *cachep, void *objp,
 {
         struct array_cache *ac = cpu_cache_get(cachep);
 
+        kasan_slab_free(cachep, objp);
+
         check_irq_off();
         kmemleak_free_recursive(objp, cachep->flags);
         objp = cache_free_debugcheck(cachep, objp, caller);
@@ -3363,6 +3378,7 @@ void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
 {
         void *ret = slab_alloc(cachep, flags, _RET_IP_);
 
+        kasan_slab_alloc(cachep, ret);
         trace_kmem_cache_alloc(_RET_IP_, ret,
                                cachep->object_size, cachep->size, flags);
 
@@ -3428,6 +3444,7 @@ kmem_cache_alloc_trace(struct kmem_cache *cachep, gfp_t flags, size_t size)
 
         ret = slab_alloc(cachep, flags, _RET_IP_);
 
+        kasan_kmalloc(cachep, ret, size);
         trace_kmalloc(_RET_IP_, ret,
                       size, cachep->size, flags);
         return ret;
@@ -3451,6 +3468,7 @@ void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
 {
         void *ret = slab_alloc_node(cachep, flags, nodeid, _RET_IP_);
 
+        kasan_slab_alloc(cachep, ret);
         trace_kmem_cache_alloc_node(_RET_IP_, ret,
                                     cachep->object_size, cachep->size,
                                     flags, nodeid);
@@ -3468,7 +3486,7 @@ void *kmem_cache_alloc_node_trace(struct kmem_cache *cachep,
         void *ret;
 
         ret = slab_alloc_node(cachep, flags, nodeid, _RET_IP_);
-
+        kasan_kmalloc(cachep, ret, size);
         trace_kmalloc_node(_RET_IP_, ret,
                            size, cachep->size,
                            flags, nodeid);
@@ -3481,11 +3499,15 @@ static __always_inline void *
 __do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller)
 {
         struct kmem_cache *cachep;
+        void *ret;
 
         cachep = kmalloc_slab(size, flags);
         if (unlikely(ZERO_OR_NULL_PTR(cachep)))
                 return cachep;
-        return kmem_cache_alloc_node_trace(cachep, flags, node, size);
+        ret = kmem_cache_alloc_node_trace(cachep, flags, node, size);
+        kasan_kmalloc(cachep, ret, size);
+
+        return ret;
 }
 
 void *__kmalloc_node(size_t size, gfp_t flags, int node)
@@ -3519,6 +3541,7 @@ static __always_inline void *__do_kmalloc(size_t size, gfp_t flags,
                 return cachep;
         ret = slab_alloc(cachep, flags, caller);
 
+        kasan_kmalloc(cachep, ret, size);
         trace_kmalloc(caller, ret,
                       size, cachep->size, flags);
 
@@ -4290,10 +4313,18 @@ module_init(slab_proc_init);
  */
 size_t ksize(const void *objp)
 {
+        size_t size;
+
         BUG_ON(!objp);
         if (unlikely(objp == ZERO_SIZE_PTR))
                 return 0;
 
-        return virt_to_cache(objp)->object_size;
+        size = virt_to_cache(objp)->object_size;
+        /* We assume that ksize callers could use the whole allocated area,
+         * so we need to unpoison this area.
+         */
+        kasan_krealloc(objp, size);
+
+        return size;
 }
 EXPORT_SYMBOL(ksize);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index b2e379639a5b..4de72e220c82 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -35,7 +35,7 @@ struct kmem_cache *kmem_cache;
  */
 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
                 SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
-                SLAB_FAILSLAB)
+                SLAB_FAILSLAB | SLAB_KASAN)
 
 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
                          SLAB_NOTRACK | SLAB_ACCOUNT)