From: "Darrick J. Wong" djwong@kernel.org
commit 1ec9307fc066dd8a140d5430f8a7576aa9d78cd3 upstream.
For a very very long time, inode inactivation has set the inode size to zero before unmapping the extents associated with the data fork. Unfortunately, commit 3c6f46eacd876 changed the inode verifier to prohibit zero-length symlinks and directories. If an inode happens to get logged in this state and the system crashes before freeing the inode, log recovery will also fail on the broken inode.
Therefore, allow zero-size symlinks and directories as long as the link count is zero; nobody will be able to open these files by handle so there isn't any risk of data exposure.
Fixes: 3c6f46eacd876 ("xfs: sanity check directory inode di_size") Signed-off-by: Darrick J. Wong djwong@kernel.org Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Chandan Babu R chandanbabu@kernel.org Signed-off-by: Catherine Hoang catherine.hoang@oracle.com Acked-by: Darrick J. Wong djwong@kernel.org --- fs/xfs/libxfs/xfs_inode_buf.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-)
diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c index 51fdd29c4ddc..423d39b6b917 100644 --- a/fs/xfs/libxfs/xfs_inode_buf.c +++ b/fs/xfs/libxfs/xfs_inode_buf.c @@ -371,10 +371,13 @@ xfs_dinode_verify_fork( /* * A directory small enough to fit in the inode must be stored * in local format. The directory sf <-> extents conversion - * code updates the directory size accordingly. + * code updates the directory size accordingly. Directories + * being truncated have zero size and are not subject to this + * check. */ if (S_ISDIR(mode)) { - if (be64_to_cpu(dip->di_size) <= fork_size && + if (dip->di_size && + be64_to_cpu(dip->di_size) <= fork_size && fork_format != XFS_DINODE_FMT_LOCAL) return __this_address; } @@ -512,9 +515,19 @@ xfs_dinode_verify( if (mode && xfs_mode_to_ftype(mode) == XFS_DIR3_FT_UNKNOWN) return __this_address;
- /* No zero-length symlinks/dirs. */ - if ((S_ISLNK(mode) || S_ISDIR(mode)) && di_size == 0) - return __this_address; + /* + * No zero-length symlinks/dirs unless they're unlinked and hence being + * inactivated. + */ + if ((S_ISLNK(mode) || S_ISDIR(mode)) && di_size == 0) { + if (dip->di_version > 1) { + if (dip->di_nlink) + return __this_address; + } else { + if (dip->di_onlink) + return __this_address; + } + }
fa = xfs_dinode_verify_nrext64(mp, dip); if (fa)