[PATCH 3.12 073/181] lz4: ensure length does not wrap

[Jiri Slaby]

From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

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@xxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 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 df6839e3ce08..99a03acb7d47 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;
 		}
 
-- 
2.0.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/