[PATCH 5.11 046/152] mptcp: fix DATA_FIN processing for orphaned sockets

Greg Kroah-Hartman
2021-04-05T09:16:52Z

From: Paolo Abeni <pabeni@redhat.com>

[ Upstream commit 341c65242fe18aac8900e4291d472df9f7ba7bc7 ]

Currently we move orphaned msk sockets directly from FIN_WAIT2
state to CLOSE, with the rationale that incoming additional
data could be just dropped by the TCP stack/TW sockets.

Anyhow we miss sending MPTCP-level ack on incoming DATA_FIN,
and that may hang the peers.

Fixes: e16163b6e2b7 ("mptcp: refactor shutdown and close")
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/mptcp/protocol.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 67483e561b37..88f2d900a347 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2292,13 +2292,12 @@ static void mptcp_worker(struct work_struct *work)
__mptcp_check_send_data_fin(sk);
mptcp_check_data_fin(sk);

- /* if the msk data is completely acked, or the socket timedout,
- * there is no point in keeping around an orphaned sk
+ /* There is no point in keeping around an orphaned sk timedout or
+ * closed, but we need the msk around to reply to incoming DATA_FIN,
+ * even if it is orphaned and in FIN_WAIT2 state
*/
if (sock_flag(sk, SOCK_DEAD) &&
- (mptcp_check_close_timeout(sk) ||
- (state != sk->sk_state &&
- ((1 << inet_sk_state_load(sk)) & (TCPF_CLOSE | TCPF_FIN_WAIT2))))) {
+ (mptcp_check_close_timeout(sk) || sk->sk_state == TCP_CLOSE)) {
inet_sk_state_store(sk, TCP_CLOSE);
__mptcp_destroy_sock(sk);
goto unlock;
--
2.30.1