[PATCH 4.0 087/148] ext4: check for zero length extent explicitly

From	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Newsgroups	linux.kernel
Subject	[PATCH 4.0 087/148] ext4: check for zero length extent explicitly
Date	2015-06-03 14:30 +0200
Message-ID	<pxfY2-SD-115@gated-at.bofh.it> (permalink)
References	<pxfOh-E4-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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

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

From: Eryu Guan <guaneryu@gmail.com>

commit 2f974865ffdfe7b9f46a9940836c8b167342563d upstream.

The following commit introduced a bug when checking for zero length extent

5946d08 ext4: check for overlapping extents in ext4_valid_extent_entries()

Zero length extent could pass the check if lblock is zero.

Adding the explicit check for zero length back.

Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/ext4/extents.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -377,7 +377,7 @@ static int ext4_valid_extent(struct inod
 	ext4_lblk_t lblock = le32_to_cpu(ext->ee_block);
 	ext4_lblk_t last = lblock + len - 1;
 
-	if (lblock > last)
+	if (len == 0 || lblock > last)
 		return 0;
 	return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, len);
 }


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[PATCH 4.0 087/148] ext4: check for zero length extent explicitly Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2015-06-03 14:30 +0200

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