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@xxxxxxxxx>
> > Suggested-by : Julia Lawall <julia.lawall@xxxxxxx>
> > Reviewed-by : Julia Lawall <julia.lawall@xxxxxxx>
> > ---
> > 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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