[PATCH 3.16.y-ckt 067/135] decompress_bunzip2: off by one in get_next_block()

[Luis Henriques]

3.16.7-ckt6 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter at oracle.com>

commit b5c8afe5be51078a979d86ae5ae78c4ac948063d upstream.

"origPtr" is used as an offset into the bd->dbuf[] array.  That array is
allocated in start_bunzip() and has "bd->dbufSize" number of elements so
the test here should be >= instead of >.

Later we check "origPtr" again before using it as an offset so I don't
know if this bug can be triggered in real life.

Fixes: bc22c17e12c1 ('bzip2/lzma: library support for gzip, bzip2 and lzma decompression')
Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
Cc: Alain Knaff <alain at knaff.lu>
Cc: Yinghai Lu <yinghai at kernel.org>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 lib/decompress_bunzip2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/decompress_bunzip2.c b/lib/decompress_bunzip2.c
index 31c5f7675fbf..f504027d66a8 100644
--- a/lib/decompress_bunzip2.c
+++ b/lib/decompress_bunzip2.c
@@ -184,7 +184,7 @@ static int INIT get_next_block(struct bunzip_data *bd)
 	if (get_bits(bd, 1))
 		return RETVAL_OBSOLETE_INPUT;
 	origPtr = get_bits(bd, 24);
-	if (origPtr > dbufSize)
+	if (origPtr >= dbufSize)
 		return RETVAL_DATA_ERROR;
 	/* mapping table: if some byte values are never used (encoding things
 	   like ascii text), the compression code removes the gaps to have fewer
-- 
2.1.4