[patch 38/39] ext4: Initialize the new group descriptor whenresizing the filesystem

[Greg KH]

2.6.28-stable review patch.  If anyone has any objections, please let us know.

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

From: "Theodore Ts'o" <tytso@xxxxxxx>
(cherry picked from commit fdff73f094e7220602cc3f8959c7230517976412)

Make sure all of the fields of the group descriptor are properly
initialized.  Previously, we allowed bg_flags field to be contain
random garbage, which could trigger non-deterministic behavior,
including a kernel OOPS.

http://bugzilla.kernel.org/show_bug.cgi?id=12433

Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 fs/ext4/resize.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -860,11 +860,13 @@ int ext4_group_add(struct super_block *s
 	gdp = (struct ext4_group_desc *)((char *)primary->b_data +
 					 gdb_off * EXT4_DESC_SIZE(sb));
 
+	memset(gdp, 0, EXT4_DESC_SIZE(sb));
 	ext4_block_bitmap_set(sb, gdp, input->block_bitmap); /* LV FIXME */
 	ext4_inode_bitmap_set(sb, gdp, input->inode_bitmap); /* LV FIXME */
 	ext4_inode_table_set(sb, gdp, input->inode_table); /* LV FIXME */
 	gdp->bg_free_blocks_count = cpu_to_le16(input->free_blocks_count);
 	gdp->bg_free_inodes_count = cpu_to_le16(EXT4_INODES_PER_GROUP(sb));
+	gdp->bg_flags = cpu_to_le16(EXT4_BG_INODE_ZEROED);
 	gdp->bg_checksum = ext4_group_desc_csum(sbi, input->group, gdp);
 
 	/*

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