mm, kasan: switch SLUB to stackdepot, enable memory quarantine for SLUB

For KASAN builds:
 - switch SLUB allocator to using stackdepot instead of storing the
   allocation/deallocation stacks in the objects;
 - change the freelist hook so that parts of the freelist can be put
   into the quarantine.

[aryabinin@virtuozzo.com: fixes]
Link: http://lkml.kernel.org/r/1468601423-28676-1-git-send-email-aryabinin@virtuozzo.com
Link: http://lkml.kernel.org/r/1468347165-41906-3-git-send-email-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <adech.fo@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Steven Rostedt (Red Hat) <rostedt@goodmis.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Kuthonuzo Luruo <kuthonuzo.luruo@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index ac4b3c4..c9cf374 100644 (file)
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -77,6 +77,7 @@ void kasan_free_shadow(const struct vm_struct *vm);
 
 size_t ksize(const void *);
 static inline void kasan_unpoison_slab(const void *ptr) { ksize(ptr); }
+size_t kasan_metadata_size(struct kmem_cache *cache);
 
 #else /* CONFIG_KASAN */
 
@@ -121,6 +122,7 @@ static inline int kasan_module_alloc(void *addr, size_t size) { return 0; }
 static inline void kasan_free_shadow(const struct vm_struct *vm) {}
 
 static inline void kasan_unpoison_slab(const void *ptr) { }
+static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
 
 #endif /* CONFIG_KASAN */
 

diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index 339ba02..4ad2c5a 100644 (file)
--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h
@@ -88,7 +88,8 @@ struct kmem_cache {
 };
 
 static inline void *nearest_obj(struct kmem_cache *cache, struct page *page,
-                               void *x) {
+                               void *x)
+{
        void *object = x - (x - page->s_mem) % cache->size;
        void *last_object = page->s_mem + (cache->num - 1) * cache->size;
 

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index cf501cf..75f56c2 100644 (file)
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -104,6 +104,10 @@ struct kmem_cache {
        unsigned int *random_seq;
 #endif
 
+#ifdef CONFIG_KASAN
+       struct kasan_cache kasan_info;
+#endif
+
        struct kmem_cache_node *node[MAX_NUMNODES];
 };
 

diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 67d8c68..bd38aab 100644 (file)
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -5,9 +5,9 @@ if HAVE_ARCH_KASAN
 
 config KASAN
        bool "KASan: runtime memory debugger"
-       depends on SLUB_DEBUG || (SLAB && !DEBUG_SLAB)
+       depends on SLUB || (SLAB && !DEBUG_SLAB)
        select CONSTRUCTORS
-       select STACKDEPOT if SLAB
+       select STACKDEPOT
        help
          Enables kernel address sanitizer - runtime memory debugger,
          designed to find out-of-bounds accesses and use-after-free bugs.

diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index 1548749..2976a9e 100644 (file)
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -7,5 +7,4 @@ CFLAGS_REMOVE_kasan.o = -pg
 # see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
 CFLAGS_kasan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
 
-obj-y := kasan.o report.o kasan_init.o
-obj-$(CONFIG_SLAB) += quarantine.o
+obj-y := kasan.o report.o kasan_init.o quarantine.o

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 6845f92..b6f99e8 100644 (file)
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -351,7 +351,6 @@ 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.
@@ -373,16 +372,8 @@ 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;
+       int orig_size = *size;
+
        /* Add alloc meta. */
        cache->kasan_info.alloc_meta_offset = *size;
        *size += sizeof(struct kasan_alloc_meta);
@@ -395,14 +386,26 @@ void kasan_cache_create(struct kmem_cache *cache, size_t *size,
        }
        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)));
+
+       *size = min(KMALLOC_MAX_SIZE, max(*size, cache->object_size +
+                                       optimal_redzone(cache->object_size)));
+
+       /*
+        * If the metadata doesn't fit, don't enable KASAN at all.
+        */
+       if (*size <= cache->kasan_info.alloc_meta_offset ||
+                       *size <= cache->kasan_info.free_meta_offset) {
+               cache->kasan_info.alloc_meta_offset = 0;
+               cache->kasan_info.free_meta_offset = 0;
+               *size = orig_size;
+               return;
+       }
+
+       *flags |= SLAB_KASAN;
 }
-#endif
 
 void kasan_cache_shrink(struct kmem_cache *cache)
 {
@@ -414,6 +417,14 @@ void kasan_cache_destroy(struct kmem_cache *cache)
        quarantine_remove_cache(cache);
 }
 
+size_t kasan_metadata_size(struct kmem_cache *cache)
+{
+       return (cache->kasan_info.alloc_meta_offset ?
+               sizeof(struct kasan_alloc_meta) : 0) +
+               (cache->kasan_info.free_meta_offset ?
+               sizeof(struct kasan_free_meta) : 0);
+}
+
 void kasan_poison_slab(struct page *page)
 {
        kasan_poison_shadow(page_address(page),
@@ -431,16 +442,13 @@ 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
 }
 
-#ifdef CONFIG_SLAB
 static inline int in_irqentry_text(unsigned long ptr)
 {
        return (ptr >= (unsigned long)&__irqentry_text_start &&
@@ -501,7 +509,6 @@ struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
        BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32);
        return (void *)object + cache->kasan_info.free_meta_offset;
 }
-#endif
 
 void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags)
 {
@@ -522,16 +529,16 @@ static void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
 
 bool kasan_slab_free(struct kmem_cache *cache, void *object)
 {
-#ifdef CONFIG_SLAB
        /* RCU slabs could be legally used after free within the RCU period */
        if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
                return false;
 
        if (likely(cache->flags & SLAB_KASAN)) {
-               struct kasan_alloc_meta *alloc_info =
-                       get_alloc_info(cache, object);
-               struct kasan_free_meta *free_info =
-                       get_free_info(cache, object);
+               struct kasan_alloc_meta *alloc_info;
+               struct kasan_free_meta *free_info;
+
+               alloc_info = get_alloc_info(cache, object);
+               free_info = get_free_info(cache, object);
 
                switch (alloc_info->state) {
                case KASAN_STATE_ALLOC:
@@ -550,10 +557,6 @@ bool kasan_slab_free(struct kmem_cache *cache, void *object)
                }
        }
        return false;
-#else
-       kasan_poison_slab_free(cache, object);
-       return false;
-#endif
 }
 
 void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
@@ -576,7 +579,6 @@ 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);
@@ -585,7 +587,6 @@ void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
                alloc_info->alloc_size = size;
                set_track(&alloc_info->track, flags);
        }
-#endif
 }
 EXPORT_SYMBOL(kasan_kmalloc);
 

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index fb87923..31972cd 100644 (file)
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -95,7 +95,6 @@ struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
 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)
@@ -110,7 +109,7 @@ static inline bool kasan_report_enabled(void)
 void kasan_report(unsigned long addr, size_t size,
                bool is_write, unsigned long ip);
 
-#ifdef CONFIG_SLAB
+#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB)
 void quarantine_put(struct kasan_free_meta *info, struct kmem_cache *cache);
 void quarantine_reduce(void);
 void quarantine_remove_cache(struct kmem_cache *cache);

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index b3c122d..861b977 100644 (file)
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -116,7 +116,6 @@ 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\n", track->pid);
@@ -130,8 +129,8 @@ static void print_track(struct kasan_track *track)
        }
 }
 
-static void object_err(struct kmem_cache *cache, struct page *page,
-                       void *object, char *unused_reason)
+static void kasan_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;
@@ -162,7 +161,6 @@ static void object_err(struct kmem_cache *cache, struct page *page,
                break;
        }
 }
-#endif
 
 static void print_address_description(struct kasan_access_info *info)
 {
@@ -177,7 +175,7 @@ static void print_address_description(struct kasan_access_info *info)
                        struct kmem_cache *cache = page->slab_cache;
                        object = nearest_obj(cache, page,
                                                (void *)info->access_addr);
-                       object_err(cache, page, object,
+                       kasan_object_err(cache, page, object,
                                        "kasan: bad access detected");
                        return;
                }

diff --git a/mm/slab.h b/mm/slab.h
index f33980a..9653f2e 100644 (file)
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -369,6 +369,8 @@ static inline size_t slab_ksize(const struct kmem_cache *s)
        if (s->flags & (SLAB_RED_ZONE | SLAB_POISON))
                return s->object_size;
 # endif
+       if (s->flags & SLAB_KASAN)
+               return s->object_size;
        /*
         * If we have the need to store the freelist pointer
         * back there or track user information then we can

diff --git a/mm/slub.c b/mm/slub.c
index 1cdde1a..74e7c8c 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -454,8 +454,6 @@ static inline void *restore_red_left(struct kmem_cache *s, void *p)
  */
 #if defined(CONFIG_SLUB_DEBUG_ON)
 static int slub_debug = DEBUG_DEFAULT_FLAGS;
-#elif defined(CONFIG_KASAN)
-static int slub_debug = SLAB_STORE_USER;
 #else
 static int slub_debug;
 #endif
@@ -660,6 +658,8 @@ static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
        if (s->flags & SLAB_STORE_USER)
                off += 2 * sizeof(struct track);
 
+       off += kasan_metadata_size(s);
+
        if (off != size_from_object(s))
                /* Beginning of the filler is the free pointer */
                print_section("Padding ", p + off, size_from_object(s) - off);
@@ -787,6 +787,8 @@ static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
                /* We also have user information there */
                off += 2 * sizeof(struct track);
 
+       off += kasan_metadata_size(s);
+
        if (size_from_object(s) == off)
                return 1;
 
@@ -1322,8 +1324,10 @@ static inline void kfree_hook(const void *x)
        kasan_kfree_large(x);
 }
 
-static inline void slab_free_hook(struct kmem_cache *s, void *x)
+static inline void *slab_free_hook(struct kmem_cache *s, void *x)
 {
+       void *freeptr;
+
        kmemleak_free_recursive(x, s->flags);
 
        /*
@@ -1344,7 +1348,13 @@ static inline void slab_free_hook(struct kmem_cache *s, void *x)
        if (!(s->flags & SLAB_DEBUG_OBJECTS))
                debug_check_no_obj_freed(x, s->object_size);
 
+       freeptr = get_freepointer(s, 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);
+       return freeptr;
 }
 
 static inline void slab_free_freelist_hook(struct kmem_cache *s,
@@ -1362,11 +1372,11 @@ static inline void slab_free_freelist_hook(struct kmem_cache *s,
 
        void *object = head;
        void *tail_obj = tail ? : head;
+       void *freeptr;
 
        do {
-               slab_free_hook(s, object);
-       } while ((object != tail_obj) &&
-                (object = get_freepointer(s, object)));
+               freeptr = slab_free_hook(s, object);
+       } while ((object != tail_obj) && (object = freeptr));
 #endif
 }
 
@@ -2878,16 +2888,13 @@ slab_empty:
  * same page) possible by specifying head and tail ptr, plus objects
  * count (cnt). Bulk free indicated by tail pointer being set.
  */
-static __always_inline void slab_free(struct kmem_cache *s, struct page *page,
-                                     void *head, void *tail, int cnt,
-                                     unsigned long addr)
+static __always_inline void do_slab_free(struct kmem_cache *s,
+                               struct page *page, void *head, void *tail,
+                               int cnt, unsigned long addr)
 {
        void *tail_obj = tail ? : head;
        struct kmem_cache_cpu *c;
        unsigned long tid;
-
-       slab_free_freelist_hook(s, head, tail);
-
 redo:
        /*
         * Determine the currently cpus per cpu slab.
@@ -2921,6 +2928,27 @@ redo:
 
 }
 
+static __always_inline void slab_free(struct kmem_cache *s, struct page *page,
+                                     void *head, void *tail, int cnt,
+                                     unsigned long addr)
+{
+       slab_free_freelist_hook(s, head, tail);
+       /*
+        * slab_free_freelist_hook() could have put the items into quarantine.
+        * If so, no need to free them.
+        */
+       if (s->flags & SLAB_KASAN && !(s->flags & SLAB_DESTROY_BY_RCU))
+               return;
+       do_slab_free(s, page, head, tail, cnt, addr);
+}
+
+#ifdef CONFIG_KASAN
+void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr)
+{
+       do_slab_free(cache, virt_to_head_page(x), x, NULL, 1, addr);
+}
+#endif
+
 void kmem_cache_free(struct kmem_cache *s, void *x)
 {
        s = cache_from_obj(s, x);
@@ -3363,7 +3391,7 @@ static void set_min_partial(struct kmem_cache *s, unsigned long min)
 static int calculate_sizes(struct kmem_cache *s, int forced_order)
 {
        unsigned long flags = s->flags;
-       unsigned long size = s->object_size;
+       size_t size = s->object_size;
        int order;
 
        /*
@@ -3422,7 +3450,10 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
                 * the object.
                 */
                size += 2 * sizeof(struct track);
+#endif
 
+       kasan_cache_create(s, &size, &s->flags);
+#ifdef CONFIG_SLUB_DEBUG
        if (flags & SLAB_RED_ZONE) {
                /*
                 * Add some empty padding so that we can catch