Re: [PATCH] USB: core: WARN if pipe direction != setup packet direction

[Alan Stern <stern@rowland.harvard.edu>]

On Fri, May 21, 2021 at 03:17:46PM +0200, Johan Hovold wrote:
> On Fri, May 21, 2021 at 10:03:26AM +0200, Johan Hovold wrote:
> > So first, this should probably be rate limited.
> 
> This could actually be done using WARN_ON_ONCE() as we don't have to
> worry about syzbot fuzzing descriptors here (all control endpoints are
> bidirectional).
> 
> > Second, did you try to estimate how many call sites that get this wrong?
> > I always felt a bit pedantic when pointing out that the pipe direction
> > should match the request type to driver author's during review when (in
> > almost all cases?) this hasn't really mattered. I fear we may have
> > accumulated a fairly large number of these mismatches over the years but
> > I haven't verified that.
> 
> I did a quick review of all ctrlpipe-macro uses in usb/misc and
> usb/serial and found two instances.
> 
> A simple grep pattern looking for explicit USB_DIR/ctrlpipe mismatches
> caught another five tree wide (not including the
> sound/usb/mixer_scarlett_gen2.c which Geoffrey reported), but there are
> likely more of those out there as the request type is often not that
> explicit.
> 
> I've prepared patches for the above, excluding the sound driver Geoffrey
> said he was fixing.

Many thanks for making the effort to do this.

Alan Stern