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

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

On 8/17/2024 7:13 PM, 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.
>
> Thanks,
> Selva


Hi Greg,

Would you like to provide any feedback or suggestions regarding the my 
last comments mentioned above?

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