答复: [PATCH] usb: xhci: check Null pointer in segment alloc

胡连勤
2025-12-22T12:21:14Z

Hi Michal:

> On Mon, 22 Dec 2025 08:13:21 +0100, Greg Kroah-Hartman wrote:
> > > An API that insists on its users exercising care, knowledge and
> > > cognisance sounds fragile and vulnerable.
> >
> > Fragile yes, vulnerable no. Let's fix the fragility then, but as has
> > been pointed out in this thread, we don't know the root cause, and I
> > don't even think this "fix" would do the right thing anyway.
>
> The patch looks wrong. I suspect this happens when add_endpoint() is called
> concurrently with resume(), which makes little sense. And it means the same
> code can probably call add_endpoint() before resume(), which makes no
> sense either. We can't do that with suspended HW.
>
> Chances are that this crash isn't even the only thing that could go wrong
> when such calls are attempted. For one, xhci_resume() drops the spinlock
> after reporting usb_root_hub_lost_power(), so your guess elsewhere was
> correct - this code isn't even locked properly.
>
> It seems no operations on USB devices during resume() are expected.

Currently, after checking the logic of our KO section,
we found that there might be two places simultaneously calling snd_usb_autoresume to wake up the headset device.

Thanks