Re: [PATCH 1/2] USB: dwc3: qcom: fix NULL-deref on suspend

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Wed, Jun 07, 2023 at 12:05:39PM +0200, Johan Hovold wrote:
> The Qualcomm dwc3 glue driver is currently accessing the driver data of
> the child core device during suspend and on wakeup interrupts. This is
> clearly a bad idea as the child may not have probed yet or could have
> been unbound from its driver.
> 
> The first such layering violation was part of the initial version of the
> driver, but this was later made worse when the hack that accesses the
> driver data of the grand child xhci device to configure the wakeup
> interrupts was added.
> 
> Fixing this properly is not that easily done, so add a sanity check to
> make sure that the child driver data is non-NULL before dereferencing it
> for now.
> 
> Note that this relies on subtleties like the fact that driver core is
> making sure that the parent is not suspended while the child is probing.
> 
> Reported-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> Link: https://lore.kernel.org/all/20230325165217.31069-4-manivannan.sadhasivam@linaro.org/
> Fixes: d9152161b4bf ("usb: dwc3: Add Qualcomm DWC3 glue layer driver")
> Fixes: 6895ea55c385 ("usb: dwc3: qcom: Configure wakeup interrupts during suspend")
> Cc: stable@vger.kernel.org	# 3.18: a872ab303d5d: "usb: dwc3: qcom: fix use-after-free on runtime-PM wakeup"
> Cc: Sandeep Maheswaram <quic_c_sanm@quicinc.com>
> Cc: Krishna Kurapati <quic_kriskura@quicinc.com>
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

- Mani

> ---
>  drivers/usb/dwc3/dwc3-qcom.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
> index 959fc925ca7c..79b22abf9727 100644
> --- a/drivers/usb/dwc3/dwc3-qcom.c
> +++ b/drivers/usb/dwc3/dwc3-qcom.c
> @@ -308,7 +308,16 @@ static void dwc3_qcom_interconnect_exit(struct dwc3_qcom *qcom)
>  /* Only usable in contexts where the role can not change. */
>  static bool dwc3_qcom_is_host(struct dwc3_qcom *qcom)
>  {
> -	struct dwc3 *dwc = platform_get_drvdata(qcom->dwc3);
> +	struct dwc3 *dwc;
> +
> +	/*
> +	 * FIXME: Fix this layering violation.
> +	 */
> +	dwc = platform_get_drvdata(qcom->dwc3);
> +
> +	/* Core driver may not have probed yet. */
> +	if (!dwc)
> +		return false;
>  
>  	return dwc->xhci;
>  }
> -- 
> 2.39.3
> 

-- 
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