[PATCH (urgent)] vfs: fix uninitialized uid/gid in chown_common()

[Christian Brauner]

On Mon, Sep 19, 2022 at 08:05:12PM +0900, Tetsuo Handa wrote:
> syzbot is reporting uninit-value in tomoyo_path_chown() [1], for
> chown_common() is by error passing uninitialized newattrs.ia_vfsuid to
> security_path_chown() via from_vfsuid() when user == -1 is passed.
> We must initialize newattrs.ia_vfs{u,g}id fields in order to make
> from_vfs{u,g}id() work.
> 
> Link: https://syzkaller.appspot.com/bug?extid=541e21dcc32c4046cba9 [1]
> Reported-by: syzbot <syzbot+541e21dcc32c4046cba9 at syzkaller.appspotmail.com>
> Signed-off-by: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
> ---

Odd that we didn't get any of the reports. Thanks for relying this.
I'll massage this a tiny bit, apply and will test with syzbot.