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authorPaolo Abeni <pabeni@redhat.com>2023-07-04 23:44:34 +0300
committerDavid S. Miller <davem@davemloft.net>2023-07-05 12:51:14 +0300
commit0226436acf2495cde4b93e7400e5a87305c26054 (patch)
tree97023eff199cd0b3adaae7eea9d4aa47ec24c505
parent3fffa15bfef48b0ad6424779c03e68ae8ace5acb (diff)
downloadlinux-0226436acf2495cde4b93e7400e5a87305c26054.tar.xz
mptcp: do not rely on implicit state check in mptcp_listen()
Since the blamed commit, closing the first subflow resets the first subflow socket state to SS_UNCONNECTED. The current mptcp listen implementation relies only on such state to prevent touching not-fully-disconnected sockets. Incoming mptcp fastclose (or paired endpoint removal) unconditionally closes the first subflow. All the above allows an incoming fastclose followed by a listen() call to successfully race with a blocking recvmsg(), potentially causing the latter to hit a divide by zero bug in cleanup_rbuf/__tcp_select_window(). Address the issue explicitly checking the msk socket state in mptcp_listen(). An alternative solution would be moving the first subflow socket state update into mptcp_disconnect(), but in the long term the first subflow socket should be removed: better avoid relaying on it for internal consistency check. Fixes: b29fcfb54cd7 ("mptcp: full disconnect implementation") Cc: stable@vger.kernel.org Reported-by: Christoph Paasch <cpaasch@apple.com> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/414 Signed-off-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net> Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/mptcp/protocol.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 489a3defdde5..3613489eb6e3 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3703,6 +3703,11 @@ static int mptcp_listen(struct socket *sock, int backlog)
pr_debug("msk=%p", msk);
lock_sock(sk);
+
+ err = -EINVAL;
+ if (sock->state != SS_UNCONNECTED || sock->type != SOCK_STREAM)
+ goto unlock;
+
ssock = __mptcp_nmpc_socket(msk);
if (IS_ERR(ssock)) {
err = PTR_ERR(ssock);