Right now in tcp_bpf_recvmsg, sock read data first from sk_receive_queue if not empty than psock->ingress_msg otherwise. If a FIN packet arrives and there's also some data in psock->ingress_msg, the data in psock->ingress_msg will be purged. It is always happen when request to a HTTP1.0 server like python SimpleHTTPServer since the server send FIN packet after data is sent out.

Fixes: 604326b41a6fb ("bpf, sockmap: convert to generic sk_msg interface") Reported-by: Arika Chen eaglesora@gmail.com Suggested-by: Arika Chen eaglesora@gmail.com Signed-off-by: Lingpeng Chen forrest0579@gmail.com Signed-off-by: John Fastabend john.fastabend@gmail.com Cc: stable@vger.kernel.org # v4.20+ Acked-by: Song Liu songliubraving@fb.com --- net/ipv4/tcp_bpf.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index e38705165ac9..e6b08b5a0895 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -121,14 +121,14 @@ int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, struct sk_psock *psock; int copied, ret;

- if (unlikely(flags & MSG_ERRQUEUE)) - return inet_recv_error(sk, msg, len, addr_len); - if (!skb_queue_empty(&sk->sk_receive_queue)) - return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); - psock = sk_psock_get(sk); if (unlikely(!psock)) return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); + if (unlikely(flags & MSG_ERRQUEUE)) + return inet_recv_error(sk, msg, len, addr_len); + if (!skb_queue_empty(&sk->sk_receive_queue) && + sk_psock_queue_empty(psock)) + return tcp_recvmsg(sk, msg, len, nonblock, flags, addr_len); lock_sock(sk); msg_bytes_ready: copied = __tcp_bpf_recvmsg(sk, psock, msg, len, flags); @@ -139,7 +139,7 @@ int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, timeo = sock_rcvtimeo(sk, nonblock); data = tcp_bpf_wait_data(sk, psock, flags, timeo, &err); if (data) { - if (skb_queue_empty(&sk->sk_receive_queue)) + if (!sk_psock_queue_empty(psock)) goto msg_bytes_ready; release_sock(sk); sk_psock_put(sk, psock);