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

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

On 8/22/2024 1:29 PM, Greg KH wrote:
> 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.

Thank you for the support!!.

Thanks,
Selva
>
> greg k-h
>