linux-kernel - [PATCH AUTOSEL for 4.9 151/156] udf: Avoid overflow when session starts at large offset

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Date:   Thu, 7 Dec 2017 15:49:33 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Jan Kara <jack@...e.cz>, alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.9 151/156] udf: Avoid overflow when session
 starts at large offset

From: Jan Kara <jack@...e.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@...an.edu.pl>
Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 fs/udf/super.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index 4942549e7dc8..4b1f6d5372c3 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -710,7 +710,7 @@ static loff_t udf_check_vsd(struct super_block *sb)
 	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),
-- 
2.11.0