Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Rejecting non-native endian BTF overlapped with the addition
of support for it.

The rest were more simple overlapping changes, except the
renesas ravb binding update, which had to follow a file
move as well as a YAML conversion.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 25 insertions, 7 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 20f89078fa8d..c15ca207dd85 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -948,21 +948,34 @@ struct tcp_sacktag_state {
 	struct rate_sample *rate;
 };
 
-/* Take a notice that peer is sending D-SACKs */
+/* Take a notice that peer is sending D-SACKs. Skip update of data delivery
+ * and spurious retransmission information if this DSACK is unlikely caused by
+ * sender's action:
+ * - DSACKed sequence range is larger than maximum receiver's window.
+ * - Total no. of DSACKed segments exceed the total no. of retransmitted segs.
+ */
 static u32 tcp_dsack_seen(struct tcp_sock *tp, u32 start_seq,
 			  u32 end_seq, struct tcp_sacktag_state *state)
 {
 	u32 seq_len, dup_segs = 1;
 
-	if (before(start_seq, end_seq)) {
-		seq_len = end_seq - start_seq;
-		if (seq_len > tp->mss_cache)
-			dup_segs = DIV_ROUND_UP(seq_len, tp->mss_cache);
-	}
+	if (!before(start_seq, end_seq))
+		return 0;
+
+	seq_len = end_seq - start_seq;
+	/* Dubious DSACK: DSACKed range greater than maximum advertised rwnd */
+	if (seq_len > tp->max_window)
+		return 0;
+	if (seq_len > tp->mss_cache)
+		dup_segs = DIV_ROUND_UP(seq_len, tp->mss_cache);
+
+	tp->dsack_dups += dup_segs;
+	/* Skip the DSACK if dup segs weren't retransmitted by sender */
+	if (tp->dsack_dups > tp->total_retrans)
+		return 0;
 
 	tp->rx_opt.sack_ok |= TCP_DSACK_SEEN;
 	tp->rack.dsack_seen = 1;
-	tp->dsack_dups += dup_segs;
 
 	state->flag |= FLAG_DSACKING_ACK;
 	/* A spurious retransmission is delivered */
@@ -1215,6 +1228,11 @@ static bool tcp_check_dsack(struct sock *sk, const struct sk_buff *ack_skb,
 	}
 
 	dup_segs = tcp_dsack_seen(tp, start_seq_0, end_seq_0, state);
+	if (!dup_segs) {	/* Skip dubious DSACK */
+		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDSACKIGNOREDDUBIOUS);
+		return false;
+	}
+
 	NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPDSACKRECVSEGS, dup_segs);
 
 	/* D-SACK for already forgotten data... Do dumb counting. */