1 files changed, 81 insertions, 47 deletions

diff --git a/mm/slab.c b/mm/slab.c
index fa49c01225a7..78f082453481 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1670,6 +1670,14 @@ static void kmem_rcu_free(struct rcu_head *head)
 }
 
 #if DEBUG
+static bool is_debug_pagealloc_cache(struct kmem_cache *cachep)
+{
+	if (debug_pagealloc_enabled() && OFF_SLAB(cachep) &&
+		(cachep->size % PAGE_SIZE) == 0)
+		return true;
+
+	return false;
+}
 
 #ifdef CONFIG_DEBUG_PAGEALLOC
 static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
@@ -1703,6 +1711,23 @@ static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr,
 	}
 	*addr++ = 0x87654321;
 }
+
+static void slab_kernel_map(struct kmem_cache *cachep, void *objp,
+				int map, unsigned long caller)
+{
+	if (!is_debug_pagealloc_cache(cachep))
+		return;
+
+	if (caller)
+		store_stackinfo(cachep, objp, caller);
+
+	kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map);
+}
+
+#else
+static inline void slab_kernel_map(struct kmem_cache *cachep, void *objp,
+				int map, unsigned long caller) {}
+
 #endif
 
 static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val)
@@ -1781,6 +1806,9 @@ static void check_poison_obj(struct kmem_cache *cachep, void *objp)
 	int size, i;
 	int lines = 0;
 
+	if (is_debug_pagealloc_cache(cachep))
+		return;
+
 	realobj = (char *)objp + obj_offset(cachep);
 	size = cachep->object_size;
 
@@ -1846,16 +1874,8 @@ static void slab_destroy_debugcheck(struct kmem_cache *cachep,
 		void *objp = index_to_obj(cachep, page, i);
 
 		if (cachep->flags & SLAB_POISON) {
-#ifdef CONFIG_DEBUG_PAGEALLOC
-			if (cachep->size % PAGE_SIZE == 0 &&
-					OFF_SLAB(cachep))
-				kernel_map_pages(virt_to_page(objp),
-					cachep->size / PAGE_SIZE, 1);
-			else
-				check_poison_obj(cachep, objp);
-#else
 			check_poison_obj(cachep, objp);
-#endif
+			slab_kernel_map(cachep, objp, 1, 0);
 		}
 		if (cachep->flags & SLAB_RED_ZONE) {
 			if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
@@ -2179,7 +2199,6 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
 		else
 			size += BYTES_PER_WORD;
 	}
-#if FORCED_DEBUG && defined(CONFIG_DEBUG_PAGEALLOC)
 	/*
 	 * To activate debug pagealloc, off-slab management is necessary
 	 * requirement. In early phase of initialization, small sized slab
@@ -2187,14 +2206,14 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
 	 * to check size >= 256. It guarantees that all necessary small
 	 * sized slab is initialized in current slab initialization sequence.
 	 */
-	if (!slab_early_init && size >= kmalloc_size(INDEX_NODE) &&
+	if (debug_pagealloc_enabled() && (flags & SLAB_POISON) &&
+		!slab_early_init && size >= kmalloc_size(INDEX_NODE) &&
 		size >= 256 && cachep->object_size > cache_line_size() &&
 		ALIGN(size, cachep->align) < PAGE_SIZE) {
 		cachep->obj_offset += PAGE_SIZE - ALIGN(size, cachep->align);
 		size = PAGE_SIZE;
 	}
 #endif
-#endif
 
 	/*
 	 * Determine if the slab management is 'on' or 'off' slab.
@@ -2237,15 +2256,6 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
 	if (flags & CFLGS_OFF_SLAB) {
 		/* really off slab. No need for manual alignment */
 		freelist_size = calculate_freelist_size(cachep->num, 0);
-
-#ifdef CONFIG_PAGE_POISONING
-		/* If we're going to use the generic kernel_map_pages()
-		 * poisoning, then it's going to smash the contents of
-		 * the redzone and userword anyhow, so switch them off.
-		 */
-		if (size % PAGE_SIZE == 0 && flags & SLAB_POISON)
-			flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
-#endif
 	}
 
 	cachep->colour_off = cache_line_size();
@@ -2261,7 +2271,19 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags)
 	cachep->size = size;
 	cachep->reciprocal_buffer_size = reciprocal_value(size);
 
-	if (flags & CFLGS_OFF_SLAB) {
+#if DEBUG
+	/*
+	 * If we're going to use the generic kernel_map_pages()
+	 * poisoning, then it's going to smash the contents of
+	 * the redzone and userword anyhow, so switch them off.
+	 */
+	if (IS_ENABLED(CONFIG_PAGE_POISONING) &&
+		(cachep->flags & SLAB_POISON) &&
+		is_debug_pagealloc_cache(cachep))
+		cachep->flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
+#endif
+
+	if (OFF_SLAB(cachep)) {
 		cachep->freelist_cache = kmalloc_slab(freelist_size, 0u);
 		/*
 		 * This is a possibility for one of the kmalloc_{dma,}_caches.
@@ -2488,9 +2510,6 @@ static void cache_init_objs(struct kmem_cache *cachep,
 	for (i = 0; i < cachep->num; i++) {
 		void *objp = index_to_obj(cachep, page, i);
 #if DEBUG
-		/* need to poison the objs? */
-		if (cachep->flags & SLAB_POISON)
-			poison_obj(cachep, objp, POISON_FREE);
 		if (cachep->flags & SLAB_STORE_USER)
 			*dbg_userword(cachep, objp) = NULL;
 
@@ -2514,10 +2533,11 @@ static void cache_init_objs(struct kmem_cache *cachep,
 				slab_error(cachep, "constructor overwrote the"
 					   " start of an object");
 		}
-		if ((cachep->size % PAGE_SIZE) == 0 &&
-			    OFF_SLAB(cachep) && cachep->flags & SLAB_POISON)
-			kernel_map_pages(virt_to_page(objp),
-					 cachep->size / PAGE_SIZE, 0);
+		/* need to poison the objs? */
+		if (cachep->flags & SLAB_POISON) {
+			poison_obj(cachep, objp, POISON_FREE);
+			slab_kernel_map(cachep, objp, 0, 0);
+		}
 #else
 		if (cachep->ctor)
 			cachep->ctor(objp);
@@ -2736,17 +2756,8 @@ static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
 
 	set_obj_status(page, objnr, OBJECT_FREE);
 	if (cachep->flags & SLAB_POISON) {
-#ifdef CONFIG_DEBUG_PAGEALLOC
-		if ((cachep->size % PAGE_SIZE)==0 && OFF_SLAB(cachep)) {
-			store_stackinfo(cachep, objp, caller);
-			kernel_map_pages(virt_to_page(objp),
-					 cachep->size / PAGE_SIZE, 0);
-		} else {
-			poison_obj(cachep, objp, POISON_FREE);
-		}
-#else
 		poison_obj(cachep, objp, POISON_FREE);
-#endif
+		slab_kernel_map(cachep, objp, 0, caller);
 	}
 	return objp;
 }
@@ -2873,15 +2884,8 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
 	if (!objp)
 		return objp;
 	if (cachep->flags & SLAB_POISON) {
-#ifdef CONFIG_DEBUG_PAGEALLOC
-		if ((cachep->size % PAGE_SIZE) == 0 && OFF_SLAB(cachep))
-			kernel_map_pages(virt_to_page(objp),
-					 cachep->size / PAGE_SIZE, 1);
-		else
-			check_poison_obj(cachep, objp);
-#else
 		check_poison_obj(cachep, objp);
-#endif
+		slab_kernel_map(cachep, objp, 1, 0);
 		poison_obj(cachep, objp, POISON_INUSE);
 	}
 	if (cachep->flags & SLAB_STORE_USER)
@@ -4229,6 +4233,36 @@ static int __init slab_proc_init(void)
 module_init(slab_proc_init);
 #endif
 
+#ifdef CONFIG_HARDENED_USERCOPY
+/*
+ * Rejects objects that are incorrectly sized.
+ *
+ * Returns NULL if check passes, otherwise const char * to name of cache
+ * to indicate an error.
+ */
+const char *__check_heap_object(const void *ptr, unsigned long n,
+				struct page *page)
+{
+	struct kmem_cache *cachep;
+	unsigned int objnr;
+	unsigned long offset;
+
+	/* Find and validate object. */
+	cachep = page->slab_cache;
+	objnr = obj_to_index(cachep, page, (void *)ptr);
+	BUG_ON(objnr >= cachep->num);
+
+	/* Find offset within object. */
+	offset = ptr - index_to_obj(cachep, page, objnr) - obj_offset(cachep);
+
+	/* Allow address range falling entirely within object size. */
+	if (offset <= cachep->object_size && n <= cachep->object_size - offset)
+		return NULL;
+
+	return cachep->name;
+}
+#endif /* CONFIG_HARDENED_USERCOPY */
+
 /**
  * ksize - get the actual amount of memory allocated for a given object
  * @objp: Pointer to the object