From 53eb4c383deb97b59f1755fe3035ec7992488375 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Thu, 23 Jul 2020 13:02:30 +0200 Subject: [PATCH] mptcp: avoid data corruption on reinsert 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 Tested-by: Christoph Paasch Signed-off-by: Paolo Abeni Signed-off-by: David S. Miller --- 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); -- 2.20.1