From: Paolo Abeni pabeni@redhat.com
commit 8031b58c3a9b1db3ef68b3bd749fbee2e1e1aaa3 upstream.
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 martineau@kernel.org Fixes: 8fd738049ac3 ("mptcp: fallback in case of simultaneous connect") Cc: stable@vger.kernel.org Reported-by: Christoph Paasch cpaasch@apple.com Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/485 Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Mat Martineau martineau@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://lore.kernel.org/r/20240607-upstream-net-20240607-misc-fixes-v1-1-1ab... Signed-off-by: Jakub Kicinski kuba@kernel.org [ Conflicts in protocol.c, similar to the ones from commit 99951b62bf20 ("mptcp: ensure snd_nxt is properly initialized on connect"), with the same resolution. Note that in this version, 'snd_una' is an atomic64 type, so use atomic64_set() instead, as it is done everywhere else. ] Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org --- net/mptcp/protocol.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 36fa456f42ba..a36493bbf895 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2646,6 +2646,7 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr, mptcp_subflow_early_fallback(msk, subflow);
WRITE_ONCE(msk->write_seq, subflow->idsn); + atomic64_set(&msk->snd_una, msk->write_seq);
do_connect: err = ssock->ops->connect(ssock, uaddr, addr_len, flags);