[PATCH] um: ubd: Fix crash from option parsing

[Hajime Tazaki]

Hello,

On Wed, 20 Jan 2021 03:19:45 +0900,
Paul Lawrence wrote:
> 
> Below patch will cause NULL ptr dereferences if the optional filenames
> are not present.
> 
> Fixes: ef3ba87cb7c9 (um: ubd: Set device serial attribute from cmdline)
> Signed-off-by: Paul Lawrence <paullawrence at google.com>

This was addressed/fixed by the below patch, though that one doesn't
the first "file" variable check.

http://lists.infradead.org/pipermail/linux-um/2020-December/000983.html

There was another attempt to fix (with the same diff), btw.

http://lists.infradead.org/pipermail/linux-um/2021-January/000998.html

It seems that the patch is already queued but not upstreamed yet.

-- Hajime