path: root/net/ipv4/tcp_input.c
diff options
authorPengcheng Yang <yangpc@wangsu.com>2019-12-30 17:54:41 +0800
committerDavid S. Miller <davem@davemloft.net>2020-01-02 15:42:28 -0800
commitc9655008e7845bcfdaac10a1ed8554ec167aea88 (patch)
tree47f88a850061d17b1635abe37ab0d17238a479a5 /net/ipv4/tcp_input.c
parentnet: dsa: mv88e6xxx: force cmode write on 6141/6341 (diff)
tcp: fix "old stuff" D-SACK causing SACK to be treated as D-SACK
When we receive a D-SACK, where the sequence number satisfies: undo_marker <= start_seq < end_seq <= prior_snd_una we consider this is a valid D-SACK and tcp_is_sackblock_valid() returns true, then this D-SACK is discarded as "old stuff", but the variable first_sack_index is not marked as negative in tcp_sacktag_write_queue(). If this D-SACK also carries a SACK that needs to be processed (for example, the previous SACK segment was lost), this SACK will be treated as a D-SACK in the following processing of tcp_sacktag_write_queue(), which will eventually lead to incorrect updates of undo_retrans and reordering. Fixes: fd6dad616d4f ("[TCP]: Earlier SACK block verification & simplify access to them") Signed-off-by: Pengcheng Yang <yangpc@wangsu.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
1 files changed, 4 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 88b987ca9ebb..0238b554a1f0 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1727,8 +1727,11 @@ tcp_sacktag_write_queue(struct sock *sk, const struct sk_buff *ack_skb,
/* Ignore very old stuff early */
- if (!after(sp[used_sacks].end_seq, prior_snd_una))
+ if (!after(sp[used_sacks].end_seq, prior_snd_una)) {
+ if (i == 0)
+ first_sack_index = -1;
+ }