Commit 29249eac authored by Paolo Abeni's avatar Paolo Abeni Committed by David S. Miller

mptcp: fix data stream corruption

Maxim reported several issues when forcing a TCP transparent proxy
to use the MPTCP protocol for the inbound connections. He also
provided a clean reproducer.

The problem boils down to 'mptcp_frag_can_collapse_to()' assuming
that only MPTCP will use the given page_frag.

If others - e.g. the plain TCP protocol - allocate page fragments,
we can end-up re-using already allocated memory for mptcp_data_frag.

Fix the issue ensuring that the to-be-expanded data fragment is
located at the current page frag end.

v1 -> v2:
 - added missing fixes tag (Mat)

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/178Reported-and-tested-by: default avatarMaxim Galaganov <max@internet.ru>
Fixes: 18b683bf ("mptcp: queue data for mptcp level retransmission")
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent df6f8237
......@@ -879,12 +879,18 @@ static bool mptcp_skb_can_collapse_to(u64 write_seq,
!mpext->frozen;
}
/* we can append data to the given data frag if:
* - there is space available in the backing page_frag
* - the data frag tail matches the current page_frag free offset
* - the data frag end sequence number matches the current write seq
*/
static bool mptcp_frag_can_collapse_to(const struct mptcp_sock *msk,
const struct page_frag *pfrag,
const struct mptcp_data_frag *df)
{
return df && pfrag->page == df->page &&
pfrag->size - pfrag->offset > 0 &&
pfrag->offset == (df->offset + df->data_len) &&
df->data_seq + df->data_len == msk->write_seq;
}
......
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