[PATCH 4.4 111/115] udf: Avoid overflow when session starts at large offset

Greg Kroah-Hartman
2017-12-18T15:57:30Z

From: Jan Kara <jack@suse.cz>

[ Upstream commit abdc0eb06964fe1d2fea6dd1391b734d0590365d ]

When session starts beyond offset 2^31 the arithmetics in
udf_check_vsd() would overflow. Make sure the computation is done in
large enough type.

Reported-by: Cezary Sliwa <sliwa@ifpan.edu.pl>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/udf/super.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -705,7 +705,7 @@ static loff_t udf_check_vsd(struct super
else
sectorsize = sb->s_blocksize;

- sector += (sbi->s_session << sb->s_blocksize_bits);
+ sector += (((loff_t)sbi->s_session) << sb->s_blocksize_bits);

udf_debug("Starting at sector %u (%ld byte sectors)\n",
(unsigned int)(sector >> sb->s_blocksize_bits),