[3.11.y.z extended stable] Patch "lz4: ensure length does not wrap" has been added to staging queue

[Luis Henriques]

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

    lz4: ensure length does not wrap

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

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

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 24095819a8b0b0885e9f8243fd25ff3526c83095 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Date: Fri, 20 Jun 2014 22:01:41 -0700
Subject: lz4: ensure length does not wrap

commit 206204a1162b995e2185275167b22468c00d6b36 upstream.

Given some pathologically compressed data, lz4 could possibly decide to
wrap a few internal variables, causing unknown things to happen.  Catch
this before the wrapping happens and abort the decompression.

Reported-by: "Don A. Bailey" <donb at securitymouse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 lib/lz4/lz4_decompress.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c
index 411be80ddb46..6423f018f907 100644
--- a/lib/lz4/lz4_decompress.c
+++ b/lib/lz4/lz4_decompress.c
@@ -72,6 +72,8 @@ static int lz4_uncompress(const char *source, char *dest, int osize)
 			len = *ip++;
 			for (; len == 255; length += 255)
 				len = *ip++;
+			if (unlikely(length > (size_t)(length + len)))
+				goto _output_error;
 			length += len;
 		}

--
1.9.1