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authorxin.guo <guoxin0309@gmail.com>2025-06-26 12:34:19 +0000
committerJakub Kicinski <kuba@kernel.org>2025-06-27 15:35:03 -0700
commita041f70e573e185d5d5fdbba53f0db2fbe7257ad (patch)
tree77b7e1cc1489bce43e2d6483a59a65b640b7ce17 /net/ipv4/tcp_input.c
parent680367bc9be929235cb9d972c8614c1fe16fa67a (diff)
tcp: fix tcp_ofo_queue() to avoid including too much DUP SACK range
If the new coming segment covers more than one skbs in the ofo queue, and which seq is equal to rcv_nxt, then the sequence range that is duplicated will be sent as DUP SACK, the detail as below, in step6, the {501,2001} range is clearly including too much DUP SACK range, in violation of RFC 2883 rules. 1. client > server: Flags [.], seq 501:1001, ack 1325288529, win 20000, length 500 2. server > client: Flags [.], ack 1, [nop,nop,sack 1 {501:1001}], length 0 3. client > server: Flags [.], seq 1501:2001, ack 1325288529, win 20000, length 500 4. server > client: Flags [.], ack 1, [nop,nop,sack 2 {1501:2001} {501:1001}], length 0 5. client > server: Flags [.], seq 1:2001, ack 1325288529, win 20000, length 2000 6. server > client: Flags [.], ack 2001, [nop,nop,sack 1 {501:2001}], length 0 After this fix, the final ACK is as below: 6. server > client: Flags [.], ack 2001, options [nop,nop,sack 1 {501:1001}], length 0 [edumazet] added a new packetdrill test in the following patch. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: xin.guo <guoxin0309@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250626123420.1933835-2-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv4/tcp_input.c')
-rw-r--r--net/ipv4/tcp_input.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 19a1542883df..79e3bfb0108f 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4845,8 +4845,9 @@ static void tcp_ofo_queue(struct sock *sk)
if (before(TCP_SKB_CB(skb)->seq, dsack_high)) {
__u32 dsack = dsack_high;
+
if (before(TCP_SKB_CB(skb)->end_seq, dsack_high))
- dsack_high = TCP_SKB_CB(skb)->end_seq;
+ dsack = TCP_SKB_CB(skb)->end_seq;
tcp_dsack_extend(sk, TCP_SKB_CB(skb)->seq, dsack);
}
p = rb_next(p);