udplite: fix various data-races

udp->pcflag, udp->pcslen and udp->pcrlen reads/writes are racy.

Move udp->pcflag to udp->udp_flags for atomicity,
and add READ_ONCE()/WRITE_ONCE() annotations for pcslen and pcrlen.

Fixes: ba4e58eca8aa ("[NET]: Supporting UDP-Lite (RFC 3828) in Linux")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

2 files changed, 16 insertions, 14 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 2eeab4af17a1..c3ff984b6354 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2120,7 +2120,8 @@ static int udp_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
 	/*
 	 * 	UDP-Lite specific tests, ignored on UDP sockets
 	 */
-	if ((up->pcflag & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {
+	if (udp_test_bit(UDPLITE_RECV_CC, sk) && UDP_SKB_CB(skb)->partial_cov) {
+		u16 pcrlen = READ_ONCE(up->pcrlen);
 
 		/*
 		 * MIB statistics other than incrementing the error count are
@@ -2133,7 +2134,7 @@ static int udp_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
 		 * delivery of packets with coverage values less than a value
 		 * provided by the application."
 		 */
-		if (up->pcrlen == 0) {          /* full coverage was set  */
+		if (pcrlen == 0) {          /* full coverage was set  */
 			net_dbg_ratelimited("UDPLite: partial coverage %d while full coverage %d requested\n",
 					    UDP_SKB_CB(skb)->cscov, skb->len);
 			goto drop;
@@ -2144,9 +2145,9 @@ static int udp_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
 		 * that it wants x while sender emits packets of smaller size y.
 		 * Therefore the above ...()->partial_cov statement is essential.
 		 */
-		if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
+		if (UDP_SKB_CB(skb)->cscov < pcrlen) {
 			net_dbg_ratelimited("UDPLite: coverage %d too small, need min %d\n",
-					    UDP_SKB_CB(skb)->cscov, up->pcrlen);
+					    UDP_SKB_CB(skb)->cscov, pcrlen);
 			goto drop;
 		}
 	}
@@ -2729,8 +2730,8 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
 			val = 8;
 		else if (val > USHRT_MAX)
 			val = USHRT_MAX;
-		up->pcslen = val;
-		up->pcflag |= UDPLITE_SEND_CC;
+		WRITE_ONCE(up->pcslen, val);
+		udp_set_bit(UDPLITE_SEND_CC, sk);
 		break;
 
 	/* The receiver specifies a minimum checksum coverage value. To make
@@ -2743,8 +2744,8 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
 			val = 8;
 		else if (val > USHRT_MAX)
 			val = USHRT_MAX;
-		up->pcrlen = val;
-		up->pcflag |= UDPLITE_RECV_CC;
+		WRITE_ONCE(up->pcrlen, val);
+		udp_set_bit(UDPLITE_RECV_CC, sk);
 		break;
 
 	default:
@@ -2808,11 +2809,11 @@ int udp_lib_getsockopt(struct sock *sk, int level, int optname,
 	/* The following two cannot be changed on UDP sockets, the return is
 	 * always 0 (which corresponds to the full checksum coverage of UDP). */
 	case UDPLITE_SEND_CSCOV:
-		val = up->pcslen;
+		val = READ_ONCE(up->pcslen);
 		break;
 
 	case UDPLITE_RECV_CSCOV:
-		val = up->pcrlen;
+		val = READ_ONCE(up->pcrlen);
 		break;
 
 	default:
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 0e79d189613b..f60ba4295435 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -727,16 +727,17 @@ static int udpv6_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
 	/*
 	 * UDP-Lite specific tests, ignored on UDP sockets (see net/ipv4/udp.c).
 	 */
-	if ((up->pcflag & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {
+	if (udp_test_bit(UDPLITE_RECV_CC, sk) && UDP_SKB_CB(skb)->partial_cov) {
+		u16 pcrlen = READ_ONCE(up->pcrlen);
 
-		if (up->pcrlen == 0) {          /* full coverage was set  */
+		if (pcrlen == 0) {          /* full coverage was set  */
 			net_dbg_ratelimited("UDPLITE6: partial coverage %d while full coverage %d requested\n",
 					    UDP_SKB_CB(skb)->cscov, skb->len);
 			goto drop;
 		}
-		if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
+		if (UDP_SKB_CB(skb)->cscov < pcrlen) {
 			net_dbg_ratelimited("UDPLITE6: coverage %d too small, need min %d\n",
-					    UDP_SKB_CB(skb)->cscov, up->pcrlen);
+					    UDP_SKB_CB(skb)->cscov, pcrlen);
 			goto drop;
 		}
 	}