From: Paolo Abeni pabeni@redhat.com
mptcp_disconnect() clears the fallback bit unconditionally, without touching the associated flags.
The bit clear is safe, as no fallback operation can race with that -- all subflow are already in TCP_CLOSE status thanks to the previous FASTCLOSE -- but we need to consistently reset all the fallback related status.
Also acquire the relevant lock, to avoid fouling static analyzers.
Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Cc: stable@vger.kernel.org Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org --- net/mptcp/protocol.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index bf92cee9b5cee39e2b0831b6f7e06ce013fb6913..6a817a13b1549c3397e8fa2e315448ce2770e195 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -3142,7 +3142,16 @@ static int mptcp_disconnect(struct sock *sk, int flags) * subflow */ mptcp_destroy_common(msk, MPTCP_CF_FASTCLOSE); + + /* The first subflow is already in TCP_CLOSE status, the following + * can't overlap with a fallback anymore + */ + spin_lock_bh(&msk->fallback_lock); + msk->allow_subflows = true; + msk->allow_infinite_fallback = true; WRITE_ONCE(msk->flags, 0); + spin_unlock_bh(&msk->fallback_lock); + msk->cb_flags = 0; msk->recovery = false; WRITE_ONCE(msk->can_ack, false);