Re: [PATCH v3] usb: chipidea: ci_hdrc_imx: Also search for 'phys' phandle

[Frieder Schrempf <frieder.schrempf@kontron.de>]

On 21.09.21 13:37, Fabio Estevam wrote:
> When passing 'phys' in the devicetree to describe the USB PHY phandle
> (which is the recommended way according to
> Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt) the
> following NULL pointer dereference is observed on i.MX7 and i.MX8MM:
> 
> [    1.489344] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000098
> [    1.498170] Mem abort info:
> [    1.500966]   ESR = 0x96000044
> [    1.504030]   EC = 0x25: DABT (current EL), IL = 32 bits
> [    1.509356]   SET = 0, FnV = 0
> [    1.512416]   EA = 0, S1PTW = 0
> [    1.515569]   FSC = 0x04: level 0 translation fault
> [    1.520458] Data abort info:
> [    1.523349]   ISV = 0, ISS = 0x00000044
> [    1.527196]   CM = 0, WnR = 1
> [    1.530176] [0000000000000098] user address but active_mm is swapper
> [    1.536544] Internal error: Oops: 96000044 [#1] PREEMPT SMP
> [    1.542125] Modules linked in:
> [    1.545190] CPU: 3 PID: 7 Comm: kworker/u8:0 Not tainted 5.14.0-dirty #3
> [    1.551901] Hardware name: Kontron i.MX8MM N801X S (DT)
> [    1.557133] Workqueue: events_unbound deferred_probe_work_func
> [    1.562984] pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--)
> [    1.568998] pc : imx7d_charger_detection+0x3f0/0x510
> [    1.573973] lr : imx7d_charger_detection+0x22c/0x510
> 
> This happens because the charger functions check for the phy presence
> inside the imx_usbmisc_data structure (data->usb_phy), but the chipidea
> core populates the usb_phy passed via 'phys' inside 'struct ci_hdrc'
> (ci->usb_phy) instead.
> 
> This causes the NULL pointer dereference inside imx7d_charger_detection().
> 
> Fix it by also searching for 'phys' in case 'fsl,usbphy' is not found.
> 
> Tested on a imx7s-warp board.
> 
> Cc: stable@vger.kernel.org
> Fixes: 746f316b753a ("usb: chipidea: introduce imx7d USB charger detection")
> Reported-by: Heiko Thiery <heiko.thiery@gmail.com>
> Signed-off-by: Fabio Estevam <festevam@gmail.com>
> Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>

Tested-by: Frieder Schrempf <frieder.schrempf@kontron.de>

> ---
> Changes since v2:
> 
> - Added Frieder's reviewed-by tag.
> - Cc stable
> - Improved the commit log and fixed typo in 'dereferenced'
> 
>  drivers/usb/chipidea/ci_hdrc_imx.c | 15 ++++++++++-----
>  1 file changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/usb/chipidea/ci_hdrc_imx.c b/drivers/usb/chipidea/ci_hdrc_imx.c
> index 8b7bc10b6e8b..f1d100671ee6 100644
> --- a/drivers/usb/chipidea/ci_hdrc_imx.c
> +++ b/drivers/usb/chipidea/ci_hdrc_imx.c
> @@ -420,11 +420,16 @@ static int ci_hdrc_imx_probe(struct platform_device *pdev)
>  	data->phy = devm_usb_get_phy_by_phandle(dev, "fsl,usbphy", 0);
>  	if (IS_ERR(data->phy)) {
>  		ret = PTR_ERR(data->phy);
> -		/* Return -EINVAL if no usbphy is available */
> -		if (ret == -ENODEV)
> -			data->phy = NULL;
> -		else
> -			goto err_clk;
> +		if (ret == -ENODEV) {
> +			data->phy = devm_usb_get_phy_by_phandle(dev, "phys", 0);
> +			if (IS_ERR(data->phy)) {
> +				ret = PTR_ERR(data->phy);
> +				if (ret == -ENODEV)
> +					data->phy = NULL;
> +				else
> +					goto err_clk;
> +			}
> +		}
>  	}
>  
>  	pdata.usb_phy = data->phy;
>