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Date: Fri, 21 Oct 2016 11:17:54 +0200 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Daeho Jeong <daeho.jeong@...sung.com>, Hobin Woo <hobin.woo@...sung.com>, Theodore Tso <tytso@....edu> Subject: [PATCH 4.7 34/45] ext4: reinforce check of i_dtime when clearing high fields of uid and gid 4.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Daeho Jeong <daeho.jeong@...sung.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@...sung.com> Signed-off-by: Hobin Woo <hobin.woo@...sung.com> Signed-off-by: Theodore Ts'o <tytso@....edu> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- fs/ext4/inode.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4814,14 +4814,14 @@ 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(i_uid)); raw_inode->i_gid_high = cpu_to_le16(high_16_bits(i_gid)); - } else { - raw_inode->i_uid_high = 0; - raw_inode->i_gid_high = 0; } } else { raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(i_uid));
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