[PATCH] usb: dwc3: gadget: Fix null pointer exception

[PATCH] usb: dwc3: gadget: Fix null pointer exception

[Albert Wang]

In the endpoint interrupt functions
dwc3_gadget_endpoint_transfer_in_progress() and
dwc3_gadget_endpoint_trbs_complete() will dereference the endpoint
descriptor. But it could be cleared in __dwc3_gadget_ep_disable()
when accessory disconnected. So we need to check whether it is null
or not before dereferencing it.

Signed-off-by: Albert Wang <albertccwang@google.com>
---
 drivers/usb/dwc3/gadget.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 23de2a5a40d6..83c7344888fd 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -3252,6 +3252,9 @@ static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
 	struct dwc3		*dwc = dep->dwc;
 	bool			no_started_trb = true;
 
+	if (!dep->endpoint.desc)
+		return no_started_trb;
+
 	dwc3_gadget_ep_cleanup_completed_requests(dep, event, status);
 
 	if (dep->flags & DWC3_EP_END_TRANSFER_PENDING)
@@ -3299,6 +3302,9 @@ static void dwc3_gadget_endpoint_transfer_in_progress(struct dwc3_ep *dep,
 {
 	int status = 0;
 
+	if (!dep->endpoint.desc)
+		return;
+
 	if (usb_endpoint_xfer_isoc(dep->endpoint.desc))
 		dwc3_gadget_endpoint_frame_from_event(dep, event);
 
-- 
2.33.1.1089.g2158813163f-goog

Re: [PATCH] usb: dwc3: gadget: Fix null pointer exception

[Jack Pham]

On Thu, Nov 04, 2021 at 02:26:16PM +0800, Albert Wang wrote:
> In the endpoint interrupt functions
> dwc3_gadget_endpoint_transfer_in_progress() and
> dwc3_gadget_endpoint_trbs_complete() will dereference the endpoint
> descriptor. But it could be cleared in __dwc3_gadget_ep_disable()
> when accessory disconnected. So we need to check whether it is null
> or not before dereferencing it.
> 
> Signed-off-by: Albert Wang <albertccwang@google.com>

Nice catch.  I think this might have been caused when the call to
dwc3_remove_requests() in __dwc3_gadget_ep_disable() was moved after
the endpoint descriptors is cleared.  So you can probably add:

Fixes: f09ddcfcb8c5 ("usb: dwc3: gadget: Prevent EP queuing while
stopping transfers").

Reviewed-by: Jack Pham <quic_jackp@quicinc.com>

> ---
>  drivers/usb/dwc3/gadget.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 23de2a5a40d6..83c7344888fd 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -3252,6 +3252,9 @@ static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
>  	struct dwc3		*dwc = dep->dwc;
>  	bool			no_started_trb = true;
>  
> +	if (!dep->endpoint.desc)
> +		return no_started_trb;
> +
>  	dwc3_gadget_ep_cleanup_completed_requests(dep, event, status);
>  
>  	if (dep->flags & DWC3_EP_END_TRANSFER_PENDING)
> @@ -3299,6 +3302,9 @@ static void dwc3_gadget_endpoint_transfer_in_progress(struct dwc3_ep *dep,
>  {
>  	int status = 0;
>  
> +	if (!dep->endpoint.desc)
> +		return;
> +
>  	if (usb_endpoint_xfer_isoc(dep->endpoint.desc))
>  		dwc3_gadget_endpoint_frame_from_event(dep, event);
>  
> -- 
> 2.33.1.1089.g2158813163f-goog
> 

Re: [PATCH] usb: dwc3: gadget: Fix null pointer exception

[Albert Wang]

Ok, let me do that.

Thanks,
Albert

On Sat, Nov 6, 2021 at 9:25 AM Jack Pham <quic_jackp@quicinc.com> wrote:
>
> On Thu, Nov 04, 2021 at 02:26:16PM +0800, Albert Wang wrote:
> > In the endpoint interrupt functions
> > dwc3_gadget_endpoint_transfer_in_progress() and
> > dwc3_gadget_endpoint_trbs_complete() will dereference the endpoint
> > descriptor. But it could be cleared in __dwc3_gadget_ep_disable()
> > when accessory disconnected. So we need to check whether it is null
> > or not before dereferencing it.
> >
> > Signed-off-by: Albert Wang <albertccwang@google.com>
>
> Nice catch.  I think this might have been caused when the call to
> dwc3_remove_requests() in __dwc3_gadget_ep_disable() was moved after
> the endpoint descriptors is cleared.  So you can probably add:
>
> Fixes: f09ddcfcb8c5 ("usb: dwc3: gadget: Prevent EP queuing while
> stopping transfers").
>
> Reviewed-by: Jack Pham <quic_jackp@quicinc.com>
>
> > ---
> >  drivers/usb/dwc3/gadget.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > index 23de2a5a40d6..83c7344888fd 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -3252,6 +3252,9 @@ static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
> >       struct dwc3             *dwc = dep->dwc;
> >       bool                    no_started_trb = true;
> >
> > +     if (!dep->endpoint.desc)
> > +             return no_started_trb;
> > +
> >       dwc3_gadget_ep_cleanup_completed_requests(dep, event, status);
> >
> >       if (dep->flags & DWC3_EP_END_TRANSFER_PENDING)
> > @@ -3299,6 +3302,9 @@ static void dwc3_gadget_endpoint_transfer_in_progress(struct dwc3_ep *dep,
> >  {
> >       int status = 0;
> >
> > +     if (!dep->endpoint.desc)
> > +             return;
> > +
> >       if (usb_endpoint_xfer_isoc(dep->endpoint.desc))
> >               dwc3_gadget_endpoint_frame_from_event(dep, event);
> >
> > --
> > 2.33.1.1089.g2158813163f-goog
> >