5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 5f9238530970f2993b23dd67fdaffc552a2d2e98 ]
If the receive queue contains payload that was already received, __tcp_close() can send an unexpected RST.
Refine the code to take tp->copied_seq into account, as we already do in tcp recvmsg().
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Neal Cardwell ncardwell@google.com Reviewed-by: Kuniyuki Iwashima kuniyu@google.com Reviewed-by: Jason Xing kerneljasonxing@gmail.com Link: https://patch.msgid.link/20250903084720.1168904-2-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/tcp.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index cc0efcb4a553c..a0a5590573b03 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2359,8 +2359,8 @@ bool tcp_check_oom(struct sock *sk, int shift)
void __tcp_close(struct sock *sk, long timeout) { + bool data_was_unread = false; struct sk_buff *skb; - int data_was_unread = 0; int state;
WRITE_ONCE(sk->sk_shutdown, SHUTDOWN_MASK); @@ -2379,11 +2379,12 @@ void __tcp_close(struct sock *sk, long timeout) * reader process may not have drained the data yet! */ while ((skb = __skb_dequeue(&sk->sk_receive_queue)) != NULL) { - u32 len = TCP_SKB_CB(skb)->end_seq - TCP_SKB_CB(skb)->seq; + u32 end_seq = TCP_SKB_CB(skb)->end_seq;
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) - len--; - data_was_unread += len; + end_seq--; + if (after(end_seq, tcp_sk(sk)->copied_seq)) + data_was_unread = true; __kfree_skb(skb); }