Re: [PATCH AUTOSEL 5.13 062/114] USB: core: Avoid WARNings for 0-length descriptor requests

[Sasha Levin]

On Sat, Jul 10, 2021 at 08:23:50AM +0200, Greg Kroah-Hartman wrote:
> On Fri, Jul 09, 2021 at 10:16:56PM -0400, Sasha Levin wrote:
> > From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> >
> > [ Upstream commit 60dfe484cef45293e631b3a6e8995f1689818172 ]
> >
> > The USB core has utility routines to retrieve various types of
> > descriptors.  These routines will now provoke a WARN if they are asked
> > to retrieve 0 bytes (USB "receive" requests must not have zero
> > length), so avert this by checking the size argument at the start.
> >
> > CC: Johan Hovold <johan@xxxxxxxxxx>
> > Reported-and-tested-by: syzbot+7dbcd9ff34dc4ed45240@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Reviewed-by: Johan Hovold <johan@xxxxxxxxxx>
> > Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> > Link: https://lore.kernel.org/r/20210607152307.GD1768031@xxxxxxxxxxxxxxxxxxx
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> > ---
> >  drivers/usb/core/message.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
> > index 30e9e680c74c..4d59d927ae3e 100644
> > --- a/drivers/usb/core/message.c
> > +++ b/drivers/usb/core/message.c
> > @@ -783,6 +783,9 @@ int usb_get_descriptor(struct usb_device *dev, unsigned char type,
> >  	int i;
> >  	int result;
> >
> > +	if (size <= 0)		/* No point in asking for no data */
> > +		return -EINVAL;
> > +
> >  	memset(buf, 0, size);	/* Make sure we parse really received data */
> >
> >  	for (i = 0; i < 3; ++i) {
> > @@ -832,6 +835,9 @@ static int usb_get_string(struct usb_device *dev, unsigned short langid,
> >  	int i;
> >  	int result;
> >
> > +	if (size <= 0)		/* No point in asking for no data */
> > +		return -EINVAL;
> > +
> >  	for (i = 0; i < 3; ++i) {
> >  		/* retry on length 0 or stall; some devices are flakey */
> >  		result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
> > --
> > 2.30.2
>
> This patch should be dropped from all of the autosel branches it was
> picked to, as I do not think the USB core has been fixed up, along with
> all of the different drivers that we noticed doing this, in the stable
> trees.
>
> So please drop from everywhere at this time.

Will do, thanks!

--
Thanks,
Sasha