[3.16.y-ckt stable] Patch "ppp: deflate: never return len larger than output buffer" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ppp: deflate: never return len larger than output buffer

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt7.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 02690e11a45a5f07e25a00b47476ec1c41a6c56f Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw at strlen.de>
Date: Wed, 28 Jan 2015 10:56:04 +0100
Subject: ppp: deflate: never return len larger than output buffer

commit e2a4800e75780ccf4e6c2487f82b688ba736eb18 upstream.

When we've run out of space in the output buffer to store more data, we
will call zlib_deflate with a NULL output buffer until we've consumed
remaining input.

When this happens, olen contains the size the output buffer would have
consumed iff we'd have had enough room.

This can later cause skb_over_panic when ppp_generic skb_put()s
the returned length.

Reported-by: Iain Douglas <centos at 1n6.org.uk>
Signed-off-by: Florian Westphal <fw at strlen.de>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/ppp/ppp_deflate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ppp/ppp_deflate.c b/drivers/net/ppp/ppp_deflate.c
index 602c625d95d5..b5edc7f96a39 100644
--- a/drivers/net/ppp/ppp_deflate.c
+++ b/drivers/net/ppp/ppp_deflate.c
@@ -246,7 +246,7 @@ static int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf,
 	/*
 	 * See if we managed to reduce the size of the packet.
 	 */
-	if (olen < isize) {
+	if (olen < isize && olen <= osize) {
 		state->stats.comp_bytes += olen;
 		state->stats.comp_packets++;
 	} else {
--
2.1.4