6.6-stable review patch. If anyone has any objections, please let me know.
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From: MoYuanhao moyuanhao3676@163.com
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: cec37a6e41aa ("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-v1-1-2da992bb6f7... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/tcp_output.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -837,8 +837,10 @@ static unsigned int tcp_syn_options(stru 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; + } } }