From 5946f683636bfe3848750eb625bf5c3044744587 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Tue, 4 Jun 2024 17:12:36 +0200 Subject: [PATCH] mptcp: ensure snd_una is properly initialized on connect This is strictly related to commit fb7a0d334894 ("mptcp: ensure snd_nxt is properly initialized on connect"). It turns out that syzkaller can trigger the retransmit after fallback and before processing any other incoming packet - so that snd_una is still left uninitialized. Address the issue explicitly initializing snd_una together with snd_nxt and write_seq. Suggested-by: Mat Martineau Fixes: 8fd738049ac3 ("mptcp: fallback in case of simultaneous connect") Cc: stable@vger.kernel.org Reported-by: Christoph Paasch Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/485 Signed-off-by: Paolo Abeni --- net/mptcp/protocol.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 2f8f32cd31d364..1c5b7796daaf65 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3735,6 +3735,7 @@ static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) WRITE_ONCE(msk->write_seq, subflow->idsn); WRITE_ONCE(msk->snd_nxt, subflow->idsn); + WRITE_ONCE(msk->snd_una, subflow->idsn); if (likely(!__mptcp_check_fallback(msk))) MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVE);