| From | Ben Hutchings <> | Date | Wed, 15 Feb 2017 22:41:34 +0000 | Subject | [PATCH 3.2 018/126] ext4: reinforce check of i_dtime when clearing high fields of uid and gid |
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3.2.85-rc1 review patch. If anyone has any objections, please let me know.
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From: Daeho Jeong <daeho.jeong@samsung.com>
commit 93e3b4e6631d2a74a8cf7429138096862ff9f452 upstream.
Now, ext4_do_update_inode() clears high 16-bit fields of uid/gid of deleted and evicted inode to fix up interoperability with old kernels. However, it checks only i_dtime of an inode to determine whether the inode was deleted and evicted, and this is very risky, because i_dtime can be used for the pointer maintaining orphan inode list, too. We need to further check whether the i_dtime is being used for the orphan inode list even if the i_dtime is not NULL.
We found that high 16-bit fields of uid/gid of inode are unintentionally and permanently cleared when the inode truncation is just triggered, but not finished, and the inode metadata, whose high uid/gid bits are cleared, is written on disk, and the sudden power-off follows that in order.
Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com> Signed-off-by: Hobin Woo <hobin.woo@samsung.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- fs/ext4/inode.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4093,14 +4093,14 @@ static int ext4_do_update_inode(handle_t * Fix up interoperability with old kernels. Otherwise, old inodes get * re-used with the upper 16 bits of the uid/gid intact */ - if (!ei->i_dtime) { + if (ei->i_dtime && list_empty(&ei->i_orphan)) { + raw_inode->i_uid_high = 0; + raw_inode->i_gid_high = 0; + } else { raw_inode->i_uid_high = cpu_to_le16(high_16_bits(inode->i_uid)); raw_inode->i_gid_high = cpu_to_le16(high_16_bits(inode->i_gid)); - } else { - raw_inode->i_uid_high = 0; - raw_inode->i_gid_high = 0; } } else { raw_inode->i_uid_low =
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