[PATCH 3.2 058/152] decompress_bunzip2: off by one in get_next_block()

From: Ben Hutchings
Date: Mon Feb 16 2015 - 21:15:01 EST

3.2.67-rc1 review patch. If anyone has any objections, please let me know.


From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

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@xxxxxxxxxx>
Cc: Alain Knaff <alain@xxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
lib/decompress_bunzip2.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/lib/decompress_bunzip2.c
+++ b/lib/decompress_bunzip2.c
@@ -185,7 +185,7 @@ static int INIT get_next_block(struct bu
if (get_bits(bd, 1))
origPtr = get_bits(bd, 24);
- if (origPtr > dbufSize)
+ if (origPtr >= dbufSize)
/* mapping table: if some byte values are never used (encoding things
like ascii text), the compression code removes the gaps to have fewer

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