From: Paolo Abeni pabeni@redhat.com
commit 29249eac5225429b898f278230a6ca2baa1ae154 upstream.
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/178 Reported-and-tested-by: Maxim Galaganov max@internet.ru Fixes: 18b683bff89d ("mptcp: queue data for mptcp level retransmission") Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mptcp/protocol.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -869,12 +869,18 @@ static bool mptcp_skb_can_collapse_to(u6 !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; }