[Saucy][Trusty][CVE-2014-4611][PATCH 1/1] lz4: ensure length does not wrap

[Brad Figg]

From: Greg Kroah-Hartman <gregkh at linuxfoundation.org>

CVE-2014-2611

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>
Cc: stable <stable at vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit 206204a1162b995e2185275167b22468c00d6b36)
Signed-off-by: Brad Figg <brad.figg 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 411be80..6423f01 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