Re: [PATCH AUTOSEL 4.19 592/671] USB: usb-skeleton: fix use-after-free after driver unbind

[Greg Kroah-Hartman]

On Thu, Jan 23, 2020 at 09:22:52AM -0500, Sasha Levin wrote:
> On Fri, Jan 17, 2020 at 11:21:16AM +0100, Johan Hovold wrote:
> > On Thu, Jan 16, 2020 at 12:03:50PM -0500, Sasha Levin wrote:
> > > From: Johan Hovold <johan@xxxxxxxxxx>
> > > 
> > > [ Upstream commit 6353001852776e7eeaab4da78922d4c6f2b076af ]
> > > 
> > > The driver failed to stop its read URB on disconnect, something which
> > > could lead to a use-after-free in the completion handler after driver
> > > unbind in case the character device has been closed.
> > > 
> > > Fixes: e7389cc9a7ff ("USB: skel_read really sucks royally")
> > > Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
> > > Link: https://lore.kernel.org/r/20191009170944.30057-3-johan@xxxxxxxxxx
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> > 
> > This one isn't needed in any stable tree. As we discussed before, the
> > skeleton driver is only there for documentation purposes.
> 
> I'll drop this, but I'm curious: doesn't this mean that users will build
> on buggy example code?

They should always be grabbing the "latest" version of the file to work
off of anyway.  Given that there are very few new USB drivers anymore, I
doubt this really matters much...

thanks,

greg k-h