1 files changed, 35 insertions, 4 deletions

diff --git a/net/core/sock.c b/net/core/sock.c
index 6354863b1c68..d9eec153d531 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -919,13 +919,19 @@ static inline void sock_lock_init(struct sock *sk)
 			af_family_keys + sk->sk_family);
 }
 
+/*
+ * Copy all fields from osk to nsk but nsk->sk_refcnt must not change yet,
+ * even temporarly, because of RCU lookups. sk_node should also be left as is.
+ */
 static void sock_copy(struct sock *nsk, const struct sock *osk)
 {
 #ifdef CONFIG_SECURITY_NETWORK
 	void *sptr = nsk->sk_security;
 #endif
-
-	memcpy(nsk, osk, osk->sk_prot->obj_size);
+	BUILD_BUG_ON(offsetof(struct sock, sk_copy_start) !=
+		     sizeof(osk->sk_node) + sizeof(osk->sk_refcnt));
+	memcpy(&nsk->sk_copy_start, &osk->sk_copy_start,
+	       osk->sk_prot->obj_size - offsetof(struct sock, sk_copy_start));
 #ifdef CONFIG_SECURITY_NETWORK
 	nsk->sk_security = sptr;
 	security_sk_clone(osk, nsk);
@@ -939,8 +945,23 @@ static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
 	struct kmem_cache *slab;
 
 	slab = prot->slab;
-	if (slab != NULL)
-		sk = kmem_cache_alloc(slab, priority);
+	if (slab != NULL) {
+		sk = kmem_cache_alloc(slab, priority & ~__GFP_ZERO);
+		if (!sk)
+			return sk;
+		if (priority & __GFP_ZERO) {
+			/*
+			 * caches using SLAB_DESTROY_BY_RCU should let
+			 * sk_node.next un-modified. Special care is taken
+			 * when initializing object to zero.
+			 */
+			if (offsetof(struct sock, sk_node.next) != 0)
+				memset(sk, 0, offsetof(struct sock, sk_node.next));
+			memset(&sk->sk_node.pprev, 0,
+			       prot->obj_size - offsetof(struct sock,
+							 sk_node.pprev));
+		}
+	}
 	else
 		sk = kmalloc(prot->obj_size, priority);
 
@@ -1125,6 +1146,11 @@ struct sock *sk_clone(const struct sock *sk, const gfp_t priority)
 
 		newsk->sk_err	   = 0;
 		newsk->sk_priority = 0;
+		/*
+		 * Before updating sk_refcnt, we must commit prior changes to memory
+		 * (Documentation/RCU/rculist_nulls.txt for details)
+		 */
+		smp_wmb();
 		atomic_set(&newsk->sk_refcnt, 2);
 
 		/*
@@ -1840,6 +1866,11 @@ void sock_init_data(struct socket *sock, struct sock *sk)
 
 	sk->sk_stamp = ktime_set(-1L, 0);
 
+	/*
+	 * Before updating sk_refcnt, we must commit prior changes to memory
+	 * (Documentation/RCU/rculist_nulls.txt for details)
+	 */
+	smp_wmb();
 	atomic_set(&sk->sk_refcnt, 1);
 	atomic_set(&sk->sk_wmem_alloc, 1);
 	atomic_set(&sk->sk_drops, 0);