[PATCH 1/3] sctp: fix association hangs due to reassembly/ordering logic

[PATCH 1/3] sctp: fix association hangs due to reassembly/ordering logic

[Roberts, Lee A.]

From: Lee A. Roberts <lee.roberts@hp.com>

Resolve SCTP association hangs observed during SCTP stress
testing.  Observable symptoms include communications hangs
with data being held in the association lobby (ordering)
queue.  Close examination of reassembly/ordering queues shows
duplicated packets.

In sctp_tsnmap_grow(), correct off-by-one errors when copying
and resizing the tsnmap.  If max_tsn_seen is in the LSB of the
word, this bit can be lost, causing the corresponding packet
to be transmitted again and to be entered as a duplicate into
the SCTP reassembly/ordering queues.

Patch applies to linux-3.8 kernel.

Signed-off-by: Lee A. Roberts <lee.roberts@hp.com>
---
 net/sctp/tsnmap.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff -uprN -X linux-3.8-vanilla/Documentation/dontdiff
linux-3.8-vanilla/net/sctp/tsnmap.c linux-3.8-SCTP+1/net/sctp/tsnmap.c
--- linux-3.8-vanilla/net/sctp/tsnmap.c	2013-02-18 16:58:34.000000000
-0700
+++ linux-3.8-SCTP+1/net/sctp/tsnmap.c	2013-02-20 08:01:02.555223259
-0700
@@ -369,14 +369,15 @@ static int sctp_tsnmap_grow(struct sctp_
 	if (gap >= SCTP_TSN_MAP_SIZE)
 		return 0;
 
-	inc = ALIGN((gap - map->len),BITS_PER_LONG) + SCTP_TSN_MAP_INCREMENT;
+	inc = ALIGN((gap - map->len + 1), BITS_PER_LONG)
+		+ SCTP_TSN_MAP_INCREMENT;
 	len = min_t(u16, map->len + inc, SCTP_TSN_MAP_SIZE);
 
 	new = kzalloc(len>>3, GFP_ATOMIC);
 	if (!new)
 		return 0;
 
-	bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn);
+	bitmap_copy(new, map->tsn_map, map->max_tsn_seen - map->base_tsn + 1);
 	kfree(map->tsn_map);
 	map->tsn_map = new;
 	map->len = len;

Re: [PATCH 1/3] sctp: fix association hangs due to reassembly/ordering logic

[David Miller]

Your email client has corrupted every one of your patches, splitting up
new lines as well as making other alterations, making them useless for
us.

Please read Documentation/email-clients.txt to learn how to fix this
problem, and only resubmit your patches when you can successfully
email a patch to yourself and cleanly apply the patch you receive
in that email as-is.

Thanks.

RE: [PATCH 1/3] sctp: fix association hangs due to reassembly/ordering logic

[Roberts, Lee A.]

David,

> -----Original Message-----
> From: David Miller [mailto:davem@davemloft.net]
> Sent: Wednesday, February 20, 2013 10:53 AM
> To: Roberts, Lee A.
> Cc: linux-sctp@vger.kernel.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH 1/3] sctp: fix association hangs due to reassembly/ordering logic
> 
> 
> Your email client has corrupted every one of your patches, splitting up
> new lines as well as making other alterations, making them useless for
> us.
> 
> Please read Documentation/email-clients.txt to learn how to fix this
> problem, and only resubmit your patches when you can successfully
> email a patch to yourself and cleanly apply the patch you receive
> in that email as-is.
> 
> Thanks.

I have addressed the e-mail client issue and have successfully mailed the
patches to myself and applied them.  I will be sending updated version shortly.

I have incorporated changes and recommendations from Vlad Yasevich into
the updated patches.

                                 - Lee Roberts