linux-kernel - [PATCH 4.1 65/84] ocfs2: fix shift left overflow

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Message-Id: <20150814174212.181320462@linuxfoundation.org>
Date:	Fri, 14 Aug 2015 10:42:33 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Joseph Qi <joseph.qi@...wei.com>,
	Mark Fasheh <mfasheh@...e.com>,
	Joel Becker <jlbec@...lplan.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.1 65/84] ocfs2: fix shift left overflow

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

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

From: Joseph Qi <joseph.qi@...wei.com>

commit 32e5a2a2be6b085febaac36efff495ad65a55e6c upstream.

When using a large volume, for example 9T volume with 2T already used,
frequent creation of small files with O_DIRECT when the IO is not
cluster aligned may clear sectors in the wrong place.  This will cause
filesystem corruption.

This is because p_cpos is a u32.  When calculating the corresponding
sector it should be converted to u64 first, otherwise it may overflow.

Signed-off-by: Joseph Qi <joseph.qi@...wei.com>
Cc: Mark Fasheh <mfasheh@...e.com>
Cc: Joel Becker <jlbec@...lplan.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/ocfs2/aops.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -686,7 +686,7 @@ static int ocfs2_direct_IO_zero_extend(s
 
 	if (p_cpos && !(ext_flags & OCFS2_EXT_UNWRITTEN)) {
 		u64 s = i_size_read(inode);
-		sector_t sector = (p_cpos << (osb->s_clustersize_bits - 9)) +
+		sector_t sector = ((u64)p_cpos << (osb->s_clustersize_bits - 9)) +
 			(do_div(s, osb->s_clustersize) >> 9);
 
 		ret = blkdev_issue_zeroout(osb->sb->s_bdev, sector,
@@ -911,7 +911,7 @@ static ssize_t ocfs2_direct_IO_write(str
 		BUG_ON(!p_cpos || (ext_flags & OCFS2_EXT_UNWRITTEN));
 
 		ret = blkdev_issue_zeroout(osb->sb->s_bdev,
-				p_cpos << (osb->s_clustersize_bits - 9),
+				(u64)p_cpos << (osb->s_clustersize_bits - 9),
 				zero_len_head >> 9, GFP_NOFS, false);
 		if (ret < 0)
 			mlog_errno(ret);


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