tcp: check space before adding MPTCP SYN options

BugLink: https://bugs.launchpad.net/bugs/2102181

commit 06d64ab46f19ac12f59a1d2aa8cd196b2e4edb5b upstream.

Ensure there is enough space before adding MPTCP options in
tcp_syn_options().

Without this check, 'remaining' could underflow, and causes issues. If
there is not enough space, MPTCP should not be used.

Signed-off-by: MoYuanhao <moyuanhao3676@163.com>
Fixes: cec37a6e41 ("mptcp: Handle MP_CAPABLE options for outgoing connections")
Cc: stable@vger.kernel.org
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
[ Matt: Add Fixes, cc Stable, update Description ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241209-net-mptcp-check-space-syn-v1-1-2da992bb6f74@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Mehmet Basaran <mehmet.basaran@canonical.com>
This commit is contained in:
MoYuanhao
2025-03-13 13:21:44 +09:00
committed by Mehmet Basaran
parent 0d33123a00
commit 9d1e90a265
+4 -2
View File
@@ -881,8 +881,10 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
unsigned int size;
if (mptcp_syn_options(sk, skb, &size, &opts->mptcp)) {
opts->options |= OPTION_MPTCP;
remaining -= size;
if (remaining >= size) {
opts->options |= OPTION_MPTCP;
remaining -= size;
}
}
}