Miklos Szeredi 5e12758086 ovl: check whiteout in ovl_create_over_whiteout() ...

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: e9be9d5e76e3 ("overlay filesystem")
Cc: <stable@vger.kernel.org> # v3.18

2018-10-31 12:15:23 +01:00

..

copy_up.c

ovl: fold copy-up helpers into callers

2018-10-26 23:34:39 +02:00

dir.c

ovl: check whiteout in ovl_create_over_whiteout()

2018-10-31 12:15:23 +01:00

export.c

ovl: Modify ovl_lookup() and friends to lookup metacopy dentry

2018-07-20 09:56:09 +02:00

file.c

vfs: swap names of {do,vfs}_clone_file_range()

2018-09-24 10:54:01 +02:00

inode.c

ovl: relax permission checking on underlying layers

2018-10-26 23:34:39 +02:00

Kconfig

ovl: Provide a mount option metacopy=on/off for metadata copyup

2018-07-20 09:56:06 +02:00

Makefile

ovl: stack file ops

2018-07-18 15:44:41 +02:00

namei.c

ovl: fix error handling in ovl_verify_set_fh()

2018-10-26 23:34:39 +02:00

overlayfs.h

ovl: abstract ovl_inode lock with a helper

2018-10-26 23:34:40 +02:00

ovl_entry.h

ovl: Store lower data inode in ovl_inode

2018-07-20 09:56:11 +02:00

readdir.c

ovl: fix wrong use of impure dir cache in ovl_iterate()

2018-07-17 16:04:34 +02:00

super.c

ovl: relax requirement for non null uuid of lower fs

2018-10-26 23:34:40 +02:00

util.c

ovl: abstract ovl_inode lock with a helper

2018-10-26 23:34:40 +02:00