[PATCH] drivers: usb: gadget: udc: Fix NULL dereference

[PATCH] drivers: usb: gadget: udc: Fix NULL dereference

[Tapasweni Pathak]

This patch fixes multiple instances of null pointer dereference in this code.

ep->udc is assigned to udc. ep is just an offset from _ep. _ep is then
checked for NULL. udc is dereferenced under the NULL check for _ep, making
an invalid pointer reference.

udc is then checked for NULL, if NULL, it is then dereferenced as
udc->dev.

To fix these issues, shift assignment of udc by dereferencing ep after
null check for _ep, replace both dev_dbg statements with pr_debug.

Found using Coccinelle.

Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
Suggested-by : Julia Lawall <julia.lawall@lip6.fr>
Reviewed-by : Julia Lawall <julia.lawall@lip6.fr>
---
 drivers/usb/gadget/udc/lpc32xx_udc.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/gadget/udc/lpc32xx_udc.c b/drivers/usb/gadget/udc/lpc32xx_udc.c
index 27fd413..6398539 100644
--- a/drivers/usb/gadget/udc/lpc32xx_udc.c
+++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
@@ -1807,17 +1807,16 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
 	    !list_empty(&req->queue))
 		return -EINVAL;

-	udc = ep->udc;
-
 	if (!_ep) {
-		dev_dbg(udc->dev, "invalid ep\n");
+		pr_debug("invalid ep\n");
 		return -EINVAL;
 	}

+	udc = ep->udc;

 	if ((!udc) || (!udc->driver) ||
 	    (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
-		dev_dbg(udc->dev, "invalid device\n");
+		pr_debug("invalid device\n");
 		return -EINVAL;
 	}

--
1.7.9.5

Re: [PATCH] drivers: usb: gadget: udc: Fix NULL dereference

[Peter Chen]

On Tue, Mar 03, 2015 at 06:28:42PM +0530, Tapasweni Pathak wrote:
> This patch fixes multiple instances of null pointer dereference in this code.
> 
> ep->udc is assigned to udc. ep is just an offset from _ep. _ep is then
> checked for NULL. udc is dereferenced under the NULL check for _ep, making
> an invalid pointer reference.
> 
> udc is then checked for NULL, if NULL, it is then dereferenced as
> udc->dev.
> 
> To fix these issues, shift assignment of udc by dereferencing ep after
> null check for _ep, replace both dev_dbg statements with pr_debug.
> 
> Found using Coccinelle.
> 
> Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
> Suggested-by : Julia Lawall <julia.lawall@lip6.fr>
> Reviewed-by : Julia Lawall <julia.lawall@lip6.fr>
> ---
>  drivers/usb/gadget/udc/lpc32xx_udc.c |    7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/gadget/udc/lpc32xx_udc.c b/drivers/usb/gadget/udc/lpc32xx_udc.c
> index 27fd413..6398539 100644
> --- a/drivers/usb/gadget/udc/lpc32xx_udc.c
> +++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
> @@ -1807,17 +1807,16 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
>  	    !list_empty(&req->queue))
>  		return -EINVAL;
> 
> -	udc = ep->udc;
> -
>  	if (!_ep) {
> -		dev_dbg(udc->dev, "invalid ep\n");
> +		pr_debug("invalid ep\n");
>  		return -EINVAL;
>  	}
> 
> +	udc = ep->udc;
> 
>  	if ((!udc) || (!udc->driver) ||
>  	    (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
> -		dev_dbg(udc->dev, "invalid device\n");
> +		pr_debug("invalid device\n");
>  		return -EINVAL;
>  	}
> 

It is driver code, we'd better use dev_dbg. If _ep exists,
both ep and udc should exist. So, how about just checking
_ep at the beginning:

diff --git a/drivers/usb/gadget/udc/lpc32xx_udc.c b/drivers/usb/gadget/udc/lpc32xx_udc.c
index 27fd413..c65de0e 100644
--- a/drivers/usb/gadget/udc/lpc32xx_udc.c
+++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
@@ -1803,7 +1803,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
 	req = container_of(_req, struct lpc32xx_request, req);
 	ep = container_of(_ep, struct lpc32xx_ep, ep);
 
-	if (!_req || !_req->complete || !_req->buf ||
+	if (!_ep || !_req || !_req->complete || !_req->buf ||
 	    !list_empty(&req->queue))
 		return -EINVAL;
 
@@ -1815,8 +1815,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
 	}
 
 
-	if ((!udc) || (!udc->driver) ||
-	    (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
+	if ((!udc->driver) || (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
 		dev_dbg(udc->dev, "invalid device\n");
 		return -EINVAL;
 	}

-- 

Best Regards,
Peter Chen

Re: [PATCH] drivers: usb: gadget: udc: Fix NULL dereference

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 2886 bytes --]

On Wed, Mar 04, 2015 at 09:11:19AM +0800, Peter Chen wrote:
> On Tue, Mar 03, 2015 at 06:28:42PM +0530, Tapasweni Pathak wrote:
> > This patch fixes multiple instances of null pointer dereference in this code.
> > 
> > ep->udc is assigned to udc. ep is just an offset from _ep. _ep is then
> > checked for NULL. udc is dereferenced under the NULL check for _ep, making
> > an invalid pointer reference.
> > 
> > udc is then checked for NULL, if NULL, it is then dereferenced as
> > udc->dev.
> > 
> > To fix these issues, shift assignment of udc by dereferencing ep after
> > null check for _ep, replace both dev_dbg statements with pr_debug.
> > 
> > Found using Coccinelle.
> > 
> > Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
> > Suggested-by : Julia Lawall <julia.lawall@lip6.fr>
> > Reviewed-by : Julia Lawall <julia.lawall@lip6.fr>
> > ---
> >  drivers/usb/gadget/udc/lpc32xx_udc.c |    7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/usb/gadget/udc/lpc32xx_udc.c b/drivers/usb/gadget/udc/lpc32xx_udc.c
> > index 27fd413..6398539 100644
> > --- a/drivers/usb/gadget/udc/lpc32xx_udc.c
> > +++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
> > @@ -1807,17 +1807,16 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
> >  	    !list_empty(&req->queue))
> >  		return -EINVAL;
> > 
> > -	udc = ep->udc;
> > -
> >  	if (!_ep) {
> > -		dev_dbg(udc->dev, "invalid ep\n");
> > +		pr_debug("invalid ep\n");
> >  		return -EINVAL;
> >  	}
> > 
> > +	udc = ep->udc;
> > 
> >  	if ((!udc) || (!udc->driver) ||
> >  	    (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
> > -		dev_dbg(udc->dev, "invalid device\n");
> > +		pr_debug("invalid device\n");
> >  		return -EINVAL;
> >  	}
> > 
> 
> It is driver code, we'd better use dev_dbg. If _ep exists,
> both ep and udc should exist. So, how about just checking
> _ep at the beginning:
> 
> diff --git a/drivers/usb/gadget/udc/lpc32xx_udc.c b/drivers/usb/gadget/udc/lpc32xx_udc.c
> index 27fd413..c65de0e 100644
> --- a/drivers/usb/gadget/udc/lpc32xx_udc.c
> +++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
> @@ -1803,7 +1803,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
>  	req = container_of(_req, struct lpc32xx_request, req);
>  	ep = container_of(_ep, struct lpc32xx_ep, ep);
>  
> -	if (!_req || !_req->complete || !_req->buf ||
> +	if (!_ep || !_req || !_req->complete || !_req->buf ||
>  	    !list_empty(&req->queue))
>  		return -EINVAL;
>  
> @@ -1815,8 +1815,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
>  	}
>  
>  
> -	if ((!udc) || (!udc->driver) ||
> -	    (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
> +	if ((!udc->driver) || (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
>  		dev_dbg(udc->dev, "invalid device\n");
>  		return -EINVAL;
>  	}

what's going to happen here ?

-- 
balbi

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RE: [PATCH] drivers: usb: gadget: udc: Fix NULL dereference

[Peter Chen]

 
> > --- a/drivers/usb/gadget/udc/lpc32xx_udc.c
> > +++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
> > @@ -1803,7 +1803,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
> >  	req = container_of(_req, struct lpc32xx_request, req);
> >  	ep = container_of(_ep, struct lpc32xx_ep, ep);
> >
> > -	if (!_req || !_req->complete || !_req->buf ||
> > +	if (!_ep || !_req || !_req->complete || !_req->buf ||
> >  	    !list_empty(&req->queue))
> >  		return -EINVAL;
> >
> > @@ -1815,8 +1815,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
> >  	}
> >
> >
> > -	if ((!udc) || (!udc->driver) ||
> > -	    (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
> > +	if ((!udc->driver) || (udc->gadget.speed == USB_SPEED_UNKNOWN))
> {
> >  		dev_dbg(udc->dev, "invalid device\n");
> >  		return -EINVAL;
> >  	}
> 
> what's going to happen here ?
> 

I just changed the current code, in fact, udc->driver is impossible to NULL which
is cleared at .udc_stop. 

The speed is possible for unknown if the reset has occurred at that time.

Peter

Re: [PATCH] drivers: usb: gadget: udc: Fix NULL dereference

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 1202 bytes --]

On Tue, Mar 10, 2015 at 02:02:44AM +0000, Peter Chen wrote:
>  
> > > --- a/drivers/usb/gadget/udc/lpc32xx_udc.c
> > > +++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
> > > @@ -1803,7 +1803,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
> > >  	req = container_of(_req, struct lpc32xx_request, req);
> > >  	ep = container_of(_ep, struct lpc32xx_ep, ep);
> > >
> > > -	if (!_req || !_req->complete || !_req->buf ||
> > > +	if (!_ep || !_req || !_req->complete || !_req->buf ||
> > >  	    !list_empty(&req->queue))
> > >  		return -EINVAL;
> > >
> > > @@ -1815,8 +1815,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
> > >  	}
> > >
> > >
> > > -	if ((!udc) || (!udc->driver) ||
> > > -	    (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
> > > +	if ((!udc->driver) || (udc->gadget.speed == USB_SPEED_UNKNOWN))
> > {
> > >  		dev_dbg(udc->dev, "invalid device\n");
> > >  		return -EINVAL;
> > >  	}
> > 
> > what's going to happen here ?
> > 
> 
> I just changed the current code, in fact, udc->driver is impossible to NULL which
> is cleared at .udc_stop. 
> 
> The speed is possible for unknown if the reset has occurred at that time.

oh, alright.

-- 
balbi

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[-- Type: application/pgp-signature, Size: 819 bytes --]

RE: [PATCH] drivers: usb: gadget: udc: Fix NULL dereference

[Peter Chen]

 
> On Tue, Mar 10, 2015 at 02:02:44AM +0000, Peter Chen wrote:
> >
> > > > --- a/drivers/usb/gadget/udc/lpc32xx_udc.c
> > > > +++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
> > > > @@ -1803,7 +1803,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
> > > >  	req = container_of(_req, struct lpc32xx_request, req);
> > > >  	ep = container_of(_ep, struct lpc32xx_ep, ep);
> > > >
> > > > -	if (!_req || !_req->complete || !_req->buf ||
> > > > +	if (!_ep || !_req || !_req->complete || !_req->buf ||
> > > >  	    !list_empty(&req->queue))
> > > >  		return -EINVAL;
> > > >
> > > > @@ -1815,8 +1815,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
> > > >  	}
> > > >
> > > >
> > > > -	if ((!udc) || (!udc->driver) ||
> > > > -	    (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
> > > > +	if ((!udc->driver) || (udc->gadget.speed == USB_SPEED_UNKNOWN))
> > > {
> > > >  		dev_dbg(udc->dev, "invalid device\n");
> > > >  		return -EINVAL;
> > > >  	}
> > >
> > > what's going to happen here ?
> > >
> >
> > I just changed the current code, in fact, udc->driver is impossible to
> > NULL which is cleared at .udc_stop.
> >
> > The speed is possible for unknown if the reset has occurred at that time.
> 
> oh, alright.

Do you need me or Tapasweni send patch for this?

Peter

Re: [PATCH] drivers: usb: gadget: udc: Fix NULL dereference

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 1495 bytes --]

On Tue, Mar 10, 2015 at 03:00:49AM +0000, Peter Chen wrote:
>  
> > On Tue, Mar 10, 2015 at 02:02:44AM +0000, Peter Chen wrote:
> > >
> > > > > --- a/drivers/usb/gadget/udc/lpc32xx_udc.c
> > > > > +++ b/drivers/usb/gadget/udc/lpc32xx_udc.c
> > > > > @@ -1803,7 +1803,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
> > > > >  	req = container_of(_req, struct lpc32xx_request, req);
> > > > >  	ep = container_of(_ep, struct lpc32xx_ep, ep);
> > > > >
> > > > > -	if (!_req || !_req->complete || !_req->buf ||
> > > > > +	if (!_ep || !_req || !_req->complete || !_req->buf ||
> > > > >  	    !list_empty(&req->queue))
> > > > >  		return -EINVAL;
> > > > >
> > > > > @@ -1815,8 +1815,7 @@ static int lpc32xx_ep_queue(struct usb_ep *_ep,
> > > > >  	}
> > > > >
> > > > >
> > > > > -	if ((!udc) || (!udc->driver) ||
> > > > > -	    (udc->gadget.speed == USB_SPEED_UNKNOWN)) {
> > > > > +	if ((!udc->driver) || (udc->gadget.speed == USB_SPEED_UNKNOWN))
> > > > {
> > > > >  		dev_dbg(udc->dev, "invalid device\n");
> > > > >  		return -EINVAL;
> > > > >  	}
> > > >
> > > > what's going to happen here ?
> > > >
> > >
> > > I just changed the current code, in fact, udc->driver is impossible to
> > > NULL which is cleared at .udc_stop.
> > >
> > > The speed is possible for unknown if the reset has occurred at that time.
> > 
> > oh, alright.
> 
> Do you need me or Tapasweni send patch for this?

if there's anything to be fixed, sure.

-- 
balbi

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