From 20bc80b6f582ad1151c52ca09ab66b472768c9c8 Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@redhat.com>
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 <cpaasch@apple.com>
Fixes: ea4ca586b16f ("mptcp: refine MPTCP-level ack scheduling")
Fixes: fd8976790a6c ("mptcp: be careful on MPTCP-level ack.")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
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)
--
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