Re: [PATCH] usb: dwc3: qcom: fix NULL pointer dereference on dwc3_qcom_read_usb2_speed

[Faisal Hassan <quic_faisalh@quicinc.com>]

On 8/22/2024 3:03 PM, Greg Kroah-Hartman wrote:
> On Tue, Aug 13, 2024 at 04:48:47PM +0530, Faisal Hassan wrote:
>> Null pointer dereference occurs when accessing 'hcd' to detect speed
>> from dwc3_qcom_suspend after the xhci-hcd is unbound.
>> To avoid this issue, ensure to check for NULL in dwc3_qcom_read_usb2_speed.
>>
>> echo xhci-hcd.0.auto > /sys/bus/platform/drivers/xhci-hcd/unbind
>>   xhci_plat_remove() -> usb_put_hcd() -> hcd_release() -> kfree(hcd)
>>
>>   Unable to handle kernel NULL pointer dereference at virtual address
>>   0000000000000060
>>   Call trace:
>>    dwc3_qcom_suspend.part.0+0x17c/0x2d0 [dwc3_qcom]
>>    dwc3_qcom_runtime_suspend+0x2c/0x40 [dwc3_qcom]
>>    pm_generic_runtime_suspend+0x30/0x44
>>    __rpm_callback+0x4c/0x190
>>    rpm_callback+0x6c/0x80
>>    rpm_suspend+0x10c/0x620
>>    pm_runtime_work+0xc8/0xe0
>>    process_one_work+0x1e4/0x4f4
>>    worker_thread+0x64/0x43c
>>    kthread+0xec/0x100
>>    ret_from_fork+0x10/0x20
>>
>> Fixes: c5f14abeb52b ("usb: dwc3: qcom: fix peripheral and OTG suspend")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Faisal Hassan <quic_faisalh@quicinc.com>
>> ---
>>  drivers/usb/dwc3/dwc3-qcom.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
>> index 88fb6706a18d..0c7846478655 100644
>> --- a/drivers/usb/dwc3/dwc3-qcom.c
>> +++ b/drivers/usb/dwc3/dwc3-qcom.c
>> @@ -319,13 +319,15 @@ static bool dwc3_qcom_is_host(struct dwc3_qcom *qcom)
>>  static enum usb_device_speed dwc3_qcom_read_usb2_speed(struct dwc3_qcom *qcom, int port_index)
>>  {
>>  	struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
>> -	struct usb_device *udev;
>> +	struct usb_device __maybe_unused *udev;
> 
> This change is not relevant to this overall patch, please remove it and
> submit it separately if still needed.

Understood. I’ll remove the change from this patch and submit it
separately if it’s still required. Thank you for the feedback!

> 
> thanks,
> 
> greg k-h

Thanks,
Faisal