On Wed, Jul 8, 2020 at 3:16 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>
> Commit 9df085f3c9a2 ("ovl: relax requirement for non null uuid of lower
> fs") relaxed the requirement for non null uuid with single lower layer to
> allow enabling index and nfs_export features with single lower squashfs.
>
> Fabian reported a regression in a setup when overlay re-uses an existing
> upper layer and re-formats the lower squashfs image. Because squashfs
> has no uuid, the origin xattr in upper layer are decoded from the new
> lower layer where they may resolve to a wrong origin file and user may
> get an ESTALE or EIO error on lookup.
>
> To avoid the reported regression while still allowing the new features
> with single lower squashfs, do not allow decoding origin with lower null
> uuid unless user opted-in to one of the new features that require
> following the lower inode of non-dir upper (index, xino, metacopy).
>
> Reported-by: Fabian <godi.beat@xxxxxxx>
> Link: https://lore.kernel.org/linux-unionfs/32532923.JtPX5UtSzP@fgdesktop/
> Fixes: 9df085f3c9a2 ("ovl: relax requirement for non null uuid...")
> Cc: stable@xxxxxxxxxxxxxxx # v4.20+
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Thanks, applied.
Miklos
