Patch "tcp: eliminate negative reordering in tcp_clean_rtx_queue" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    tcp: eliminate negative reordering in tcp_clean_rtx_queue

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     tcp-eliminate-negative-reordering-in-tcp_clean_rtx_queue.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Wed May 31 09:13:34 JST 2017
From: Soheil Hassas Yeganeh <soheil@google.com>
Date: Mon, 15 May 2017 17:05:47 -0400
Subject: tcp: eliminate negative reordering in tcp_clean_rtx_queue

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 :


Patches currently in stable-queue which might be from soheil@google.com are

queue-4.9/tcp-eliminate-negative-reordering-in-tcp_clean_rtx_queue.patch
queue-4.9/net-packet-fix-missing-net_device-reference-release.patch
queue-4.9/tcp-avoid-fragmenting-peculiar-skbs-in-sack.patch