Re: [PATCH] usb: gadget: u_audio: reject srate request for unconfigured direction

[Greg KH <gregkh@linuxfoundation.org>]

On Sun, Oct 18, 2026 at 04:28:49PM +0530, Deepanshu Kartikey wrote:
> On Wed, Sep 30, 2026 at 1:48 PM Deepanshu Kartikey
> <kartikey406@gmail.com> wrote:
> >
> > On Tue, Sep 29, 2026 at 6:53 PM Greg KH <gregkh@linuxfoundation.org> wrote:
> > >
> > > On Fri, Aug 21, 2026 at 05:18:54PM +0530, Deepanshu Kartikey wrote:
> > > > u_audio_get_playback_srate() unconditionally locks and reads
> > > > uac->p_prm.lock/srate, but g_audio_setup() only initializes
> > > > p_prm.lock when p_chmask is set. On a UAC2 instance configured
> > > > without a playback direction, this results in acquiring a
> > > > never spin_lock_init()'d lock when a GET_CUR sample rate
> > > > request targets playback, triggering a lockdep "trying to
> > > > register non-static key" warning.
> > > >
> > > > Reject the request with -EOPNOTSUPP when p_chmask is not set,
> > > > before touching prm->lock.
> > > >
> > > > Fixes: eb3a1ce6f5ed ("usb: gadget: u_audio: Add capture/playback srate getter")
> > > > Reported-by: syzbot+e1d0e66badecc32d45eb@syzkaller.appspotmail.com
> > > > Closes: http://syzkaller.appspot.com/bug?extid=e1d0e66badecc32d45eb
> > > > Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
> > > > ---
> > >
> > > How was this tested?
> >
> > I have not been able to test this since there is no
> > repro present in syzbot.
> >
> > I verified the fix by static analysis of the call path in the report
> > (afunc_setup -> in_rq_cur -> u_audio_get_playback_srate) and confirmed
> > in g_audio_setup() that uac->p_prm.lock is only passed through
> > spin_lock_init() inside the "if (p_chmask)" block, so it is left
> > uninitialized whenever p_chmask is 0. Leading to lock splat issue.
> >
> > This patch is compile test only
> >
> > > Did you forget a Assisted-by: tag?
> >
> > Sure I will add assisted by tag
> >
> > thanks
> >
> > Deepanshu
> 
> Hi Greg,
> 
> Please let me know the status of this patch.

Burried with 2000+ other pending USB patches, please be patient, there
is no rush here as this is not affecting any real device you have,
right?

thanks,

greg k-h