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| author | Theodore Ts'o <tytso@mit.edu> | 2019-11-11 22:18:13 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-17 20:35:41 +0100 |
| commit | 8e7a865366105b978eef4108f49a12100eea4299 (patch) | |
| tree | 5223725d0c8895fe27dea993f5b6bdcc4dbd67d2 | |
| parent | 79bee5a380342b48d0ce177cb2fb75ef6eeeb1a2 (diff) | |
| download | linux-stable-8e7a865366105b978eef4108f49a12100eea4299.tar.gz linux-stable-8e7a865366105b978eef4108f49a12100eea4299.tar.bz2 linux-stable-8e7a865366105b978eef4108f49a12100eea4299.zip | |
ext4: work around deleting a file with i_nlink == 0 safely
commit c7df4a1ecb8579838ec8c56b2bb6a6716e974f37 upstream.
If the file system is corrupted such that a file's i_links_count is
too small, then it's possible that when unlinking that file, i_nlink
will already be zero. Previously we were working around this kind of
corruption by forcing i_nlink to one; but we were doing this before
trying to delete the directory entry --- and if the file system is
corrupted enough that ext4_delete_entry() fails, then we exit with
i_nlink elevated, and this causes the orphan inode list handling to be
FUBAR'ed, such that when we unmount the file system, the orphan inode
list can get corrupted.
A better way to fix this is to simply skip trying to call drop_nlink()
if i_nlink is already zero, thus moving the check to the place where
it makes the most sense.
https://bugzilla.kernel.org/show_bug.cgi?id=205433
Link: https://lore.kernel.org/r/20191112032903.8828-1-tytso@mit.edu
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/ext4/namei.c | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index badbb8b4f0f1..f56d6f1950b9 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -3056,18 +3056,17 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry) if (IS_DIRSYNC(dir)) ext4_handle_sync(handle); - if (inode->i_nlink == 0) { - ext4_warning_inode(inode, "Deleting file '%.*s' with no links", - dentry->d_name.len, dentry->d_name.name); - set_nlink(inode, 1); - } retval = ext4_delete_entry(handle, dir, de, bh); if (retval) goto end_unlink; dir->i_ctime = dir->i_mtime = current_time(dir); ext4_update_dx_flag(dir); ext4_mark_inode_dirty(handle, dir); - drop_nlink(inode); + if (inode->i_nlink == 0) + ext4_warning_inode(inode, "Deleting file '%.*s' with no links", + dentry->d_name.len, dentry->d_name.name); + else + drop_nlink(inode); if (!inode->i_nlink) ext4_orphan_add(handle, inode); inode->i_ctime = current_time(inode); |