[3.11.y.z extended stable] Patch "lz4: fix another possible overrun" 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: fix another possible overrun

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 5a05e9855da46131cd0ed34b29045636bf479d87 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Date: Tue, 24 Jun 2014 16:59:01 -0400
Subject: lz4: fix another possible overrun

commit 4148c1f67abf823099b2d7db6851e4aea407f5ee upstream.

There is one other possible overrun in the lz4 code as implemented by
Linux at this point in time (which differs from the upstream lz4
codebase, but will get synced at in a future kernel release.)  As
pointed out by Don, we also need to check the overflow in the data
itself.

While we are at it, replace the odd error return value with just a
"simple" -1 value as the return value is never used for anything other
than a basic "did this work or not" check.

Reported-by: "Don A. Bailey" <donb at securitymouse.com>
Reported-by: Willy Tarreau <w at 1wt.eu>
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 | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c
index 6423f018f907..8ee9333e87ae 100644
--- a/lib/lz4/lz4_decompress.c
+++ b/lib/lz4/lz4_decompress.c
@@ -108,6 +108,8 @@ static int lz4_uncompress(const char *source, char *dest, int osize)
 		if (length == ML_MASK) {
 			for (; *ip == 255; length += 255)
 				ip++;
+			if (unlikely(length > (size_t)(length + *ip)))
+				goto _output_error;
 			length += *ip++;
 		}

@@ -157,7 +159,7 @@ static int lz4_uncompress(const char *source, char *dest, int osize)

 	/* write overflow error detected */
 _output_error:
-	return (int) (-(((char *)ip) - source));
+	return -1;
 }

 static int lz4_uncompress_unknownoutputsize(const char *source, char *dest,
--
1.9.1