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 cfb8e366e229461f950e7f8b3d1235d7a4641e1f..00704312f4f75f967ea84e50a853e95ec9ec78f2 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);
 
        /*