WSL2-Linux-Kernel/fs/overlayfs
Miklos Szeredi cd09665ab6 ovl: check whiteout in ovl_create_over_whiteout()
commit 5e12758086 upstream.

Kaixuxia repors that it's possible to crash overlayfs by removing the
whiteout on the upper layer before creating a directory over it.  This is a
reproducer:

 mkdir lower upper work merge
 touch lower/file
 mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merge
 rm merge/file
 ls -al merge/file
 rm upper/file
 ls -al merge/
 mkdir merge/file

Before commencing with a vfs_rename(..., RENAME_EXCHANGE) verify that the
lookup of "upper" is positive and is a whiteout, and return ESTALE
otherwise.

Reported by: kaixuxia <xiakaixu1987@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: e9be9d5e76 ("overlay filesystem")
Cc: <stable@vger.kernel.org> # v3.18
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-11-21 09:24:17 +01:00
..
Kconfig ovl: introduce the inodes index dir feature 2017-07-04 22:03:17 +02:00
Makefile ovl: split super.c 2016-12-16 11:02:56 +01:00
copy_up.c vfs: swap names of {do,vfs}_clone_file_range() 2018-11-10 07:48:33 -08:00
dir.c ovl: check whiteout in ovl_create_over_whiteout() 2018-11-21 09:24:17 +01:00
inode.c ovl: hash non-dir by lower inode for fsnotify 2018-10-03 17:00:56 -07:00
namei.c ovl: fix error handling in ovl_verify_set_fh() 2018-11-21 09:24:04 +01:00
overlayfs.h ovl: fix format of setxattr debug 2018-10-10 08:54:27 +02:00
ovl_entry.h locking/barriers: Convert users of lockless_dereference() to READ_ONCE() 2017-12-25 14:26:21 +01:00
readdir.c ovl: fix wrong use of impure dir cache in ovl_iterate() 2018-09-09 19:55:58 +02:00
super.c ovl: Sync upper dirty data when syncing overlayfs 2018-08-03 07:50:43 +02:00
util.c ovl: fix memory leak on unlink of indexed file 2018-10-10 08:54:27 +02:00