Commit 3e674773 authored by Soheil Hassas Yeganeh's avatar Soheil Hassas Yeganeh Committed by Sasha Levin

tcp: eliminate negative reordering in tcp_clean_rtx_queue

[ Upstream commit bafbb9c7 ]

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: c7caf8d3 ("[TCP]: Fix reord detection due to snd_una covered holes")
Reported-by: default avatarRebecca Isaacs <risaacs@google.com>
Signed-off-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
parent e7b4f3d3
......@@ -3175,7 +3175,7 @@ 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 :
......
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