Re: [PATCH 01/10] USB: move snd_usb_pipe_sanity_check into the USB core

[Greg Kroah-Hartman]

On Wed, Sep 02, 2020 at 08:45:53PM -0400, Alan Stern wrote:
> On Wed, Sep 02, 2020 at 01:01:03PM +0200, Greg Kroah-Hartman wrote:
> > snd_usb_pipe_sanity_check() is a great function, so let's move it into
> > the USB core so that other parts of the kernel, including the USB core,
> > can call it.
> > 
> > Name it usb_pipe_type_check() to match the existing
> > usb_urb_ep_type_check() call, which now uses this function.
> > 
> > Cc: Jaroslav Kysela <perex@xxxxxxxx>
> > Cc: Takashi Iwai <tiwai@xxxxxxxx>
> > Cc: "Gustavo A. R. Silva" <gustavoars@xxxxxxxxxx>
> > Cc: Eli Billauer <eli.billauer@xxxxxxxxx>
> > Cc: Emiliano Ingrassia <ingrassia@xxxxxxxxxxxxxx>
> > Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> > Cc: Alexander Tsoy <alexander@xxxxxxx>
> > Cc: "Geoffrey D. Bennett" <g@xxxxx>
> > Cc: Jussi Laako <jussi@xxxxxxxxxxxxx>
> > Cc: Nick Kossifidis <mickflemm@xxxxxxxxx>
> > Cc: Dmitry Panchenko <dmitry@xxxxxxxxxxxx>
> > Cc: Chris Wulff <crwulff@xxxxxxxxx>
> > Cc: Jesus Ramos <jesus-ramos@xxxxxxxx>
> > Cc: linux-usb@xxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > Cc: alsa-devel@xxxxxxxxxxxxxxxx
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > ---
> 
> > diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
> > index 27e83e55a590..45bc2914c1ba 100644
> > --- a/drivers/usb/core/urb.c
> > +++ b/drivers/usb/core/urb.c
> > @@ -192,24 +192,39 @@ static const int pipetypes[4] = {
> >  };
> >  
> >  /**
> > - * usb_urb_ep_type_check - sanity check of endpoint in the given urb
> > - * @urb: urb to be checked
> > + * usb_pipe_type_check - sanity check of a specific pipe for a usb device
> > + * @dev: struct usb_device to be checked
> > + * @pipe: pipe to check
> >   *
> >   * This performs a light-weight sanity check for the endpoint in the
> > - * given urb.  It returns 0 if the urb contains a valid endpoint, otherwise
> > - * a negative error code.
> > + * given usb device.  It returns 0 if the pipe is a valid for the specific usb
> -----------------------------------------------------^
> Typo.

Oops, will fix, thanks.


> 
> > + * device, otherwise a negative error code.
> >   */
> > -int usb_urb_ep_type_check(const struct urb *urb)
> > +int usb_pipe_type_check(struct usb_device *dev, unsigned int pipe)
> >  {
> >  	const struct usb_host_endpoint *ep;
> >  
> > -	ep = usb_pipe_endpoint(urb->dev, urb->pipe);
> > +	ep = usb_pipe_endpoint(dev, pipe);
> >  	if (!ep)
> >  		return -EINVAL;
> > -	if (usb_pipetype(urb->pipe) != pipetypes[usb_endpoint_type(&ep->desc)])
> > +	if (usb_pipetype(pipe) != pipetypes[usb_endpoint_type(&ep->desc)])
> >  		return -EINVAL;
> >  	return 0;
> >  }
> > +EXPORT_SYMBOL_GPL(usb_pipe_type_check);
> > +
> > +/**
> > + * usb_urb_ep_type_check - sanity check of endpoint in the given urb
> > + * @urb: urb to be checked
> > + *
> > + * This performs a light-weight sanity check for the endpoint in the
> > + * given urb.  It returns 0 if the urb contains a valid endpoint, otherwise
> > + * a negative error code.
> > + */
> > +int usb_urb_ep_type_check(const struct urb *urb)
> > +{
> > +	return usb_pipe_type_check(urb->dev, urb->pipe);
> > +}
> >  EXPORT_SYMBOL_GPL(usb_urb_ep_type_check);
> 
> Since this routine is used in only one place in the entire kernel, you 
> might as well inline the code there and get rid of the function 
> entirely.

Good idea, will do.

> > diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
> > index abf99b814a0f..fc3aab04a0bc 100644
> > --- a/sound/usb/quirks.c
> > +++ b/sound/usb/quirks.c
> > @@ -846,7 +846,7 @@ static int snd_usb_accessmusic_boot_quirk(struct usb_device *dev)
> >  	static const u8 seq[] = { 0x4e, 0x73, 0x52, 0x01 };
> >  	void *buf;
> >  
> > -	if (snd_usb_pipe_sanity_check(dev, usb_sndintpipe(dev, 0x05)))
> > +	if (usb_pipe_type_check(dev, usb_sndintpipe(dev, 0x05)))
> >  		return -EINVAL;
> >  	buf = kmemdup(seq, ARRAY_SIZE(seq), GFP_KERNEL);
> >  	if (!buf)
> > @@ -875,7 +875,7 @@ static int snd_usb_nativeinstruments_boot_quirk(struct usb_device *dev)
> >  {
> >  	int ret;
> >  
> > -	if (snd_usb_pipe_sanity_check(dev, usb_sndctrlpipe(dev, 0)))
> > +	if (usb_pipe_type_check(dev, usb_sndctrlpipe(dev, 0)))
> >  		return -EINVAL;
> 
> In a few places here this check is completely unnecessary.  All it does 
> is verify that the device does have an endpoint 0 and the the type of 
> the endpoint matches the type of the pipe.  Well, every USB device 
> always has an endpoint 0, and it is always a bidirectional control 
> endpoint.

I think this was probably added to handle syzbot issues.  As long as the
USB core does ensure that a USB device has endpoint 0, I agree, these
can be removed.  I'll go check that and add a follow-on patch to the
series to do this, thanks.

thanks,

greg k-h