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

[Selvarasu Ganesan <selvarasu.g@samsung.com>]

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.

Thanks,
Selva
>
> thanks,
>
> greg k-h
>
>