ext4: Initialize the new group descriptor when resizing the filesystem

(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@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index d1585dd3af8e5beea58b16577162cedf958fde80..a0276912c1474250bfeb9a4f90b2bc6ad300ba20 100644 (file)
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -860,11 +860,13 @@ int ext4_group_add(struct super_block *sb, struct ext4_new_group_data *input)
        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);
 
        /*