linux-kernel - [PATCH 3.18 66/69] udf: Avoid overflow when session starts at large offset

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Date:   Mon, 18 Dec 2017 16:48:52 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Cezary Sliwa <sliwa@...an.edu.pl>,
        Jan Kara <jack@...e.cz>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 3.18 66/69] udf: Avoid overflow when session starts at large offset

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

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

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/udf/super.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -706,7 +706,7 @@ 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),