| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 17/94] tcp: eliminate negative reordering in tcp_clean_rtx_queue | Date | Mon, 5 Jun 2017 18:16:53 +0200 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Soheil Hassas Yeganeh <soheil@google.com>
[ Upstream commit bafbb9c73241760023d8981191ddd30bb1c6dbac ]
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 <risaacs@google.com> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3233,7 +3233,7 @@ static int tcp_clean_rtx_queue(struct so 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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