Commit 9a19371b authored Apr 22, 2020 by Paolo Abeni Committed by David S. Miller Apr 22, 2020

mptcp: fix data_fin handing in RX path



The data fin flag is set only via a DSS option, but
mptcp_incoming_options() copies it unconditionally from the
provided RX options.

Since we do not clear all the mptcp sock RX options in a
socket free/alloc cycle, we can end-up with a stray data_fin
value while parsing e.g. MPC packets.

That would lead to mapping data corruption and will trigger
a few WARN_ON() in the RX path.

Instead of adding a costly memset(), fetch the data_fin flag
only for DSS packets - when we always explicitly initialize
such bit at option parsing time.

Fixes: 648ef4b8 ("mptcp: Implement MPTCP receive path")
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent a53c1028

net/mptcp/options.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -876,12 +876,11 @@ void mptcp_incoming_options(struct sock sk, struct sk_buff skb,
		mpext->data_seq = mp_opt->data_seq;
		mpext->subflow_seq = mp_opt->subflow_seq;
		mpext->dsn64 = mp_opt->dsn64;
		mpext->data_fin = mp_opt->data_fin;
		}
		mpext->data_len = mp_opt->data_len;
		mpext->use_map = 1;
		}

		mpext->data_fin = mp_opt->data_fin;
		}

		void mptcp_write_options(__be32 ptr, struct mptcp_out_options opts)

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