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| author | Pengcheng Yang <yangpc@wangsu.com> | 2019-12-30 17:54:41 +0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2020-04-28 19:03:13 +0100 |
| commit | 88803afc2f21babbc1cb9b77cbeedcc76daa697f (patch) | |
| tree | 1a7724a1b0bf5d889102bfc99e965ea0ea0485ec /net | |
| parent | 7403ef766208bcf94b55318945f28c9ecf0db28b (diff) | |
| download | linux-stable-88803afc2f21babbc1cb9b77cbeedcc76daa697f.tar.gz linux-stable-88803afc2f21babbc1cb9b77cbeedcc76daa697f.tar.bz2 linux-stable-88803afc2f21babbc1cb9b77cbeedcc76daa697f.zip | |
tcp: fix "old stuff" D-SACK causing SACK to be treated as D-SACK
commit c9655008e7845bcfdaac10a1ed8554ec167aea88 upstream.
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_input.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index a42b6671d542..fc0425cff370 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1713,8 +1713,11 @@ 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; continue; + } used_sacks++; } |