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mptcp: fix data_fin handing in RX path

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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: 648ef4b886 ("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>
This commit is contained in:
Paolo Abeni 2020-04-22 18:24:56 +02:00 committed by David S. Miller
parent a53c102872
commit 9a19371bf0
1 changed files with 1 additions and 2 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

3
net/mptcp/options.c
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@ -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)