[U-Boot] usb: xhci: Fix a potential NULL pointer dereference

This patch fixes a potential NULL pointer dereference arising on
non-present/non-initialized xHCI controllers

Signed-off-by: Sergey Temerkhanov <s.temerkhanov@gmail.com>
Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
---

 drivers/usb/host/xhci.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

On Friday, August 14, 2015 at 02:13:06 PM, Sergey Temerkhanov wrote:
> This patch fixes a potential NULL pointer dereference arising on
> non-present/non-initialized xHCI controllers

Hi,

can you please explain how can such a condition even happen ?
I believe the hcor must always be inited at that point. What
is the condition which triggers this ?

> Signed-off-by: Sergey Temerkhanov <s.temerkhanov@gmail.com>
> Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
> ---
> 
>  drivers/usb/host/xhci.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 0b09643..a6c6659 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -199,7 +199,7 @@ int xhci_reset(struct xhci_hcor *hcor)
>  	int ret;
> 
>  	/* Halting the Host first */
> -	debug("// Halt the HC\n");
> +	debug("// Halt the HC: %p\n", hcor);
>  	state = xhci_readl(&hcor->or_usbsts) & STS_HALT;
>  	if (!state) {
>  		cmd = xhci_readl(&hcor->or_usbcmd);
> @@ -1093,9 +1093,11 @@ int usb_lowlevel_stop(int index)
>  {
>  	struct xhci_ctrl *ctrl = (xhcic + index);
> 
> -	xhci_lowlevel_stop(ctrl);
> -	xhci_hcd_stop(index);
> -	xhci_cleanup(ctrl);
> +	if (ctrl->hcor) {
> +		xhci_lowlevel_stop(ctrl);
> +		xhci_hcd_stop(index);
> +		xhci_cleanup(ctrl);
> +	}
> 
>  	return 0;
>  }

Best regards,
Marek Vasut

This may happen when, for example, one tries to get a single binary for
similar systems where those controllers may or may not present.

Regards,
Sergey

On Fri, Aug 14, 2015 at 3:15 PM, Marek Vasut <marex@denx.de> wrote:

> On Friday, August 14, 2015 at 02:13:06 PM, Sergey Temerkhanov wrote:
> > This patch fixes a potential NULL pointer dereference arising on
> > non-present/non-initialized xHCI controllers
>
> Hi,
>
> can you please explain how can such a condition even happen ?
> I believe the hcor must always be inited at that point. What
> is the condition which triggers this ?
>
> > Signed-off-by: Sergey Temerkhanov <s.temerkhanov@gmail.com>
> > Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
> > ---
> >
> >  drivers/usb/host/xhci.c | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> > index 0b09643..a6c6659 100644
> > --- a/drivers/usb/host/xhci.c
> > +++ b/drivers/usb/host/xhci.c
> > @@ -199,7 +199,7 @@ int xhci_reset(struct xhci_hcor *hcor)
> >       int ret;
> >
> >       /* Halting the Host first */
> > -     debug("// Halt the HC\n");
> > +     debug("// Halt the HC: %p\n", hcor);
> >       state = xhci_readl(&hcor->or_usbsts) & STS_HALT;
> >       if (!state) {
> >               cmd = xhci_readl(&hcor->or_usbcmd);
> > @@ -1093,9 +1093,11 @@ int usb_lowlevel_stop(int index)
> >  {
> >       struct xhci_ctrl *ctrl = (xhcic + index);
> >
> > -     xhci_lowlevel_stop(ctrl);
> > -     xhci_hcd_stop(index);
> > -     xhci_cleanup(ctrl);
> > +     if (ctrl->hcor) {
> > +             xhci_lowlevel_stop(ctrl);
> > +             xhci_hcd_stop(index);
> > +             xhci_cleanup(ctrl);
> > +     }
> >
> >       return 0;
> >  }
>
> Best regards,
> Marek Vasut
>

On Friday, August 14, 2015 at 03:00:31 PM, Sergei Temerkhanov wrote:
> This may happen when, for example, one tries to get a single binary for
> similar systems where those controllers may or may not present.

Please DO STOP TOP-POSTING, I mentioned it already, it is really not helpful.

I think your patch is missing one small bit in usb_lowlevel_init() in xhci.c
In case xhci_lowlevel_init() fails and thus the controller is NOT inited, the
usb_lowlevel_stop() will still try to unregister such controller, which will
likely fail.

You might want to add a check which sets the HCOR and HCCR to NULL if the
xhci_lowlevel_init() fails. What do you think ?

> Regards,
> Sergey
> 
> On Fri, Aug 14, 2015 at 3:15 PM, Marek Vasut <marex@denx.de> wrote:
> > On Friday, August 14, 2015 at 02:13:06 PM, Sergey Temerkhanov wrote:
> > > This patch fixes a potential NULL pointer dereference arising on
> > > non-present/non-initialized xHCI controllers
> > 
> > Hi,
> > 
> > can you please explain how can such a condition even happen ?
> > I believe the hcor must always be inited at that point. What
> > is the condition which triggers this ?
> > 
> > > Signed-off-by: Sergey Temerkhanov <s.temerkhanov@gmail.com>
> > > Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla@cavium.com>
> > > ---
> > > 
> > >  drivers/usb/host/xhci.c | 10 ++++++----
> > >  1 file changed, 6 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> > > index 0b09643..a6c6659 100644
> > > --- a/drivers/usb/host/xhci.c
> > > +++ b/drivers/usb/host/xhci.c
> > > @@ -199,7 +199,7 @@ int xhci_reset(struct xhci_hcor *hcor)
> > > 
> > >       int ret;
> > >       
> > >       /* Halting the Host first */
> > > 
> > > -     debug("// Halt the HC\n");
> > > +     debug("// Halt the HC: %p\n", hcor);
> > > 
> > >       state = xhci_readl(&hcor->or_usbsts) & STS_HALT;
> > >       if (!state) {
> > >       
> > >               cmd = xhci_readl(&hcor->or_usbcmd);
> > > 
> > > @@ -1093,9 +1093,11 @@ int usb_lowlevel_stop(int index)
> > > 
> > >  {
> > >  
> > >       struct xhci_ctrl *ctrl = (xhcic + index);
> > > 
> > > -     xhci_lowlevel_stop(ctrl);
> > > -     xhci_hcd_stop(index);
> > > -     xhci_cleanup(ctrl);
> > > +     if (ctrl->hcor) {
> > > +             xhci_lowlevel_stop(ctrl);
> > > +             xhci_hcd_stop(index);
> > > +             xhci_cleanup(ctrl);
> > > +     }
> > > 
> > >       return 0;
> > >  
> > >  }
> > 
> > Best regards,
> > Marek Vasut

Best regards,
Marek Vasut