When updating a partially acked data fragment, we actually corrupt it. This is irrelevant till we send data on a single subflow, as retransmitted data, if any are discarded by the peer as duplicate, but it will cause data corruption as soon as we will start creating non backup subflows.
Reviewed-by: Mat Martineau <[email protected]> Tested-by: Christoph Paasch <[email protected]> Signed-off-by: Paolo Abeni <[email protected]> --- net/mptcp/protocol.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 59c0eef807b3..254e6ef2b4e0 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -460,15 +460,20 @@ static void mptcp_clean_una(struct sock *sk) dfrag = mptcp_rtx_head(sk); if (dfrag && after64(snd_una, dfrag->data_seq)) { - u64 delta = dfrag->data_seq + dfrag->data_len - snd_una; + u64 delta = snd_una - dfrag->data_seq; + + if (WARN_ON_ONCE(delta > dfrag->data_len)) + goto out; dfrag->data_seq += delta; + dfrag->offset += delta; dfrag->data_len -= delta; dfrag_uncharge(sk, delta); cleaned = true; } +out: if (cleaned) { sk_mem_reclaim_partial(sk); -- 2.26.2
