From bafbb9c73241760023d8981191ddd30bb1c6dbac Mon Sep 17 00:00:00 2001 From: Soheil Hassas Yeganeh Date: Mon, 15 May 2017 17:05:47 -0400 Subject: [PATCH] tcp: eliminate negative reordering in tcp_clean_rtx_queue tcp_ack() can call tcp_fragment() which may dededuct the value tp->fackets_out when MSS changes. When prior_fackets is larger than tp->fackets_out, tcp_clean_rtx_queue() can invoke tcp_update_reordering() with negative values. This results in absurd tp->reodering values higher than sysctl_tcp_max_reordering. Note that tcp_update_reordering indeeds sets tp->reordering to min(sysctl_tcp_max_reordering, metric), but because the comparison is signed, a negative metric always wins. Fixes: c7caf8d3ed7a ("[TCP]: Fix reord detection due to snd_una covered holes") Reported-by: Rebecca Isaacs Signed-off-by: Soheil Hassas Yeganeh Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 06e2dbc..174d437 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3190,7 +3190,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets, int delta; /* Non-retransmitted hole got filled? That's reordering */ - if (reord < prior_fackets) + if (reord < prior_fackets && reord <= tp->fackets_out) tcp_update_reordering(sk, tp->fackets_out - reord, 0); delta = tcp_is_fack(tp) ? pkts_acked : -- 2.7.4