Re: [PATCH v3] usb: dwc3: core: Prevent USB core invalid event buffer address access

[Greg KH <gregkh@linuxfoundation.org>]

On Sat, Aug 17, 2024 at 07:13:53PM +0530, Selvarasu Ganesan wrote:
> 
> On 8/17/2024 10:47 AM, Greg KH wrote:
> > On Fri, Aug 16, 2024 at 09:13:09PM +0530, Selvarasu Ganesan wrote:
> >> On 8/16/2024 3:25 PM, Greg KH wrote:
> >>> On Thu, Aug 15, 2024 at 12:18:31PM +0530, Selvarasu Ganesan wrote:
> >>>> This commit addresses an issue where the USB core could access an
> >>>> invalid event buffer address during runtime suspend, potentially causing
> >>>> SMMU faults and other memory issues in Exynos platforms. The problem
> >>>> arises from the following sequence.
> >>>>           1. In dwc3_gadget_suspend, there is a chance of a timeout when
> >>>>           moving the USB core to the halt state after clearing the
> >>>>           run/stop bit by software.
> >>>>           2. In dwc3_core_exit, the event buffer is cleared regardless of
> >>>>           the USB core's status, which may lead to an SMMU faults and
> >>>>           other memory issues. if the USB core tries to access the event
> >>>>           buffer address.
> >>>>
> >>>> To prevent this hardware quirk on Exynos platforms, this commit ensures
> >>>> that the event buffer address is not cleared by software  when the USB
> >>>> core is active during runtime suspend by checking its status before
> >>>> clearing the buffer address.
> >>>>
> >>>> Cc: stable@vger.kernel.org # v6.1+
> >>> Any hint as to what commit id this fixes?
> >>>
> >>> thanks,
> >>>
> >>> greg k-h
> >>
> >> Hi Greg,
> >>
> >> This issue is not related to any particular commit. The given fix is
> >> address a hardware quirk on the Exynos platform. And we require it to be
> >> backported on stable kernel 6.1 and above all stable kernel.
> > If it's a hardware quirk issue, why are you restricting it to a specific
> > kernel release and not a specific kernel commit?  Why not 5.15?  5.4?
> 
> Hi Greg,
> 
> I mentioned a specific kernel because our platform is set to be tested 
> and functioning with kernels 6.1 and above, and the issue was reported 
> with these kernel versions. However, we would be fine if all stable 
> kernels, such as 5.4 and 5.15, were backported. In this case, if you 
> need a new patch version to update the Cc tag for all stable kernels, 
> please suggest the Cc tag to avoid confusion in next version.

I'll fix it up when applying it, thanks.

greg k-h