general protection fault in snd_ctl_release

[Al Viro]

On Wed, Sep 02, 2020 at 05:22:00PM +0200, Takashi Iwai wrote:

> Marc, Al, could you guys check this bug?

That's racy; the first one should be get_file_rcu() instead of
file_count()+get_file(), the second is not needed at all (we
have the file pinned down by the caller).  See vfs.git#work.epoll
for fix