linux-ext4 - [PATCH FOR-STABLE-2.6.27 24/24] ext4: Initialize the new group descriptor when resizing the filesystem

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Date:	Tue, 17 Feb 2009 10:58:44 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	stable@...nel.org
Cc:	linux-ext4@...r.kernel.org, Theodore Ts'o <tytso@....edu>
Subject: [PATCH FOR-STABLE-2.6.27 24/24] ext4: Initialize the new group descriptor when resizing the filesystem

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@....edu>
Cc: stable@...nel.org
(cherry picked from commit fdff73f094e7220602cc3f8959c7230517976412)
---
 fs/ext4/resize.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index cfb8e36..0070431 100644
--- 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);
 
 	/*
-- 
1.5.6.3

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