Re: [PATCH v3 1/4] usb: renesas_usbhs: gadget: fix NULL pointer dereference in ep_disable()

[Felipe Balbi <balbi@ti.com>]

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On Thu, Oct 30, 2014 at 07:30:16PM +0900, Yoshihiro Shimoda wrote:
> From: Kazuya Mizuguchi <kazuya.mizuguchi.ks@renesas.com>
> 
> This patch fixes an issue that the NULL pointer dereference happens
> when we uses g_audio driver. Since the g_audio driver will call
> usb_ep_disable() in afunc_set_alt() before it calls usb_ep_enable(),
> the uep->pipe of renesas usbhs driver will be NULL. So, this patch
> adds a condition to avoid the oops.
> 
> Signed-off-by: Kazuya Mizuguchi <kazuya.mizuguchi.ks@renesas.com>
> Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
> Cc: <stable@vger.kernel.org>
> ---
>  drivers/usb/renesas_usbhs/mod_gadget.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/usb/renesas_usbhs/mod_gadget.c b/drivers/usb/renesas_usbhs/mod_gadget.c
> index 2d17c10..2d0903f 100644
> --- a/drivers/usb/renesas_usbhs/mod_gadget.c
> +++ b/drivers/usb/renesas_usbhs/mod_gadget.c
> @@ -602,6 +602,9 @@ static int usbhsg_ep_disable(struct usb_ep *ep)
>  	struct usbhsg_uep *uep = usbhsg_ep_to_uep(ep);
>  	struct usbhs_pipe *pipe = usbhsg_uep_to_pipe(uep);
>  
> +	if (!uep || !uep->pipe)

how can uep ever be NULL ? Look at the definition of usbhsg_ep_to_uep():

	#define usbhsg_ep_to_uep(e)             container_of(e, struct usbhsg_uep, ep)

how can a container_of() ever return NULL ? What you should check if
"ep" (the argument to this function) being NULL.

-- 
balbi

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