1 files changed, 42 insertions, 14 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 14bc654b6842..447defbfccdd 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -388,7 +388,7 @@ static int compute_score(struct sock *sk, struct net *net,
 		return -1;
 	score += 4;
 
-	if (sk->sk_incoming_cpu == raw_smp_processor_id())
+	if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
 		score++;
 	return score;
 }
@@ -1297,6 +1297,27 @@ out:
 
 #define UDP_SKB_IS_STATELESS 0x80000000
 
+/* all head states (dst, sk, nf conntrack) except skb extensions are
+ * cleared by udp_rcv().
+ *
+ * We need to preserve secpath, if present, to eventually process
+ * IP_CMSG_PASSSEC at recvmsg() time.
+ *
+ * Other extensions can be cleared.
+ */
+static bool udp_try_make_stateless(struct sk_buff *skb)
+{
+	if (!skb_has_extensions(skb))
+		return true;
+
+	if (!secpath_exists(skb)) {
+		skb_ext_reset(skb);
+		return true;
+	}
+
+	return false;
+}
+
 static void udp_set_dev_scratch(struct sk_buff *skb)
 {
 	struct udp_dev_scratch *scratch = udp_skb_scratch(skb);
@@ -1308,14 +1329,24 @@ static void udp_set_dev_scratch(struct sk_buff *skb)
 	scratch->csum_unnecessary = !!skb_csum_unnecessary(skb);
 	scratch->is_linear = !skb_is_nonlinear(skb);
 #endif
-	/* all head states execept sp (dst, sk, nf) are always cleared by
-	 * udp_rcv() and we need to preserve secpath, if present, to eventually
-	 * process IP_CMSG_PASSSEC at recvmsg() time
-	 */
-	if (likely(!skb_sec_path(skb)))
+	if (udp_try_make_stateless(skb))
 		scratch->_tsize_state |= UDP_SKB_IS_STATELESS;
 }
 
+static void udp_skb_csum_unnecessary_set(struct sk_buff *skb)
+{
+	/* We come here after udp_lib_checksum_complete() returned 0.
+	 * This means that __skb_checksum_complete() might have
+	 * set skb->csum_valid to 1.
+	 * On 64bit platforms, we can set csum_unnecessary
+	 * to true, but only if the skb is not shared.
+	 */
+#if BITS_PER_LONG == 64
+	if (!skb_shared(skb))
+		udp_skb_scratch(skb)->csum_unnecessary = true;
+#endif
+}
+
 static int udp_skb_truesize(struct sk_buff *skb)
 {
 	return udp_skb_scratch(skb)->_tsize_state & ~UDP_SKB_IS_STATELESS;
@@ -1550,10 +1581,7 @@ static struct sk_buff *__first_packet_length(struct sock *sk,
 			*total += skb->truesize;
 			kfree_skb(skb);
 		} else {
-			/* the csum related bits could be changed, refresh
-			 * the scratch area
-			 */
-			udp_set_dev_scratch(skb);
+			udp_skb_csum_unnecessary_set(skb);
 			break;
 		}
 	}
@@ -1577,7 +1605,7 @@ static int first_packet_length(struct sock *sk)
 
 	spin_lock_bh(&rcvq->lock);
 	skb = __first_packet_length(sk, rcvq, &total);
-	if (!skb && !skb_queue_empty(sk_queue)) {
+	if (!skb && !skb_queue_empty_lockless(sk_queue)) {
 		spin_lock(&sk_queue->lock);
 		skb_queue_splice_tail_init(sk_queue, rcvq);
 		spin_unlock(&sk_queue->lock);
@@ -1650,7 +1678,7 @@ struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags,
 				return skb;
 			}
 
-			if (skb_queue_empty(sk_queue)) {
+			if (skb_queue_empty_lockless(sk_queue)) {
 				spin_unlock_bh(&queue->lock);
 				goto busy_check;
 			}
@@ -1676,7 +1704,7 @@ busy_check:
 				break;
 
 			sk_busy_loop(sk, flags & MSG_DONTWAIT);
-		} while (!skb_queue_empty(sk_queue));
+		} while (!skb_queue_empty_lockless(sk_queue));
 
 		/* sk_queue is empty, reader_queue may contain peeked packets */
 	} while (timeo &&
@@ -2712,7 +2740,7 @@ __poll_t udp_poll(struct file *file, struct socket *sock, poll_table *wait)
 	__poll_t mask = datagram_poll(file, sock, wait);
 	struct sock *sk = sock->sk;
 
-	if (!skb_queue_empty(&udp_sk(sk)->reader_queue))
+	if (!skb_queue_empty_lockless(&udp_sk(sk)->reader_queue))
 		mask |= EPOLLIN | EPOLLRDNORM;
 
 	/* Check for false positives due to checksum errors */