From 3ce8c99ecd940bf6bba73a3a1f6fe6f28ee4bc34 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Tue, 12 Jan 2021 18:25:23 +0100 Subject: [PATCH] mptcp: more strict state checking for acks Syzkaller found a way to trigger division by zero in mptcp_subflow_cleanup_rbuf(). The current checks implemented into tcp_can_send_ack() are too week, let's be more accurate. Reported-by: Christoph Paasch Fixes: 4b82918d43b2 ("mptcp: refine MPTCP-level ack scheduling") Fixes: 53c79b423756 ("mptcp: be careful on MPTCP-level ack.") Signed-off-by: Paolo Abeni Reviewed-by: Mat Martineau Signed-off-by: Jakub Kicinski --- net/mptcp/protocol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 6628d8d742030..2ff8c7caf74fc 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -427,7 +427,7 @@ static bool mptcp_subflow_active(struct mptcp_subflow_context *subflow) static bool tcp_can_send_ack(const struct sock *ssk) { return !((1 << inet_sk_state_load(ssk)) & - (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_TIME_WAIT | TCPF_CLOSE)); + (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_TIME_WAIT | TCPF_CLOSE | TCPF_LISTEN)); } static void mptcp_send_ack(struct mptcp_sock *msk) -- 2.39.5