This is a note to let you know that I've just added the patch titled
tcp: avoid fragmenting peculiar skbs in SACK
to the 4.4-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-avoid-fragmenting-peculiar-skbs-in-sack.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Fri Jun 2 09:29:55 JST 2017
From: Yuchung Cheng <ycheng@xxxxxxxxxx>
Date: Wed, 10 May 2017 17:01:27 -0700
Subject: tcp: avoid fragmenting peculiar skbs in SACK
From: Yuchung Cheng <ycheng@xxxxxxxxxx>
[ Upstream commit b451e5d24ba6687c6f0e7319c727a709a1846c06 ]
This patch fixes a bug in splitting an SKB during SACK
processing. Specifically if an skb contains multiple
packets and is only partially sacked in the higher sequences,
tcp_match_sack_to_skb() splits the skb and marks the second fragment
as SACKed.
The current code further attempts rounding up the first fragment
to MSS boundaries. But it misses a boundary condition when the
rounded-up fragment size (pkt_len) is exactly skb size. Spliting
such an skb is pointless and causses a kernel warning and aborts
the SACK processing. This patch universally checks such over-split
before calling tcp_fragment to prevent these unnecessary warnings.
Fixes: adb92db857ee ("tcp: Make SACK code to split only at mss boundaries")
Signed-off-by: Yuchung Cheng <ycheng@xxxxxxxxxx>
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx>
Acked-by: Neal Cardwell <ncardwell@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/tcp_input.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1134,13 +1134,14 @@ static int tcp_match_skb_to_sack(struct
*/
if (pkt_len > mss) {
unsigned int new_len = (pkt_len / mss) * mss;
- if (!in_sack && new_len < pkt_len) {
+ if (!in_sack && new_len < pkt_len)
new_len += mss;
- if (new_len >= skb->len)
- return 0;
- }
pkt_len = new_len;
}
+
+ if (pkt_len >= skb->len && !in_sack)
+ return 0;
+
err = tcp_fragment(sk, skb, pkt_len, mss, GFP_ATOMIC);
if (err < 0)
return err;
Patches currently in stable-queue which might be from ycheng@xxxxxxxxxx are
queue-4.4/tcp-eliminate-negative-reordering-in-tcp_clean_rtx_queue.patch
queue-4.4/tcp-avoid-fragmenting-peculiar-skbs-in-sack.patch