Re: [PATCH] USB: disable all RNDIS protocol drivers

Johannes Berg
2023-07-12T13:01:27Z

On Wed, 2023-07-12 at 11:22 +0200, Oliver Neukum wrote:
>
> On 04.07.23 08:47, Greg Kroah-Hartman wrote:
> > On Mon, Jul 03, 2023 at 11:11:57PM +0200, Enrico Mioso wrote:
> > > Hi all!!
> > >
> > > I think the rndis_host USB driver might emit a warning in the dmesg, but disabling the driver wouldn't be a good idea.
> > > The TP-Link MR6400 V1 LTE modem and also some ZTE modems integrated in routers do use this protocol.
> > >
> > > We may also distinguish between these cases and devices you might plug in - as they pose different risk levels.
> >
> > Again, you have to fully trust the other side of an RNDIS connection,
> > any hints on how to have the kernel determine that?

> it is a network protocol. So this statement is kind of odd.
> Are you saying that there are RNDIS messages that cannot be verified
> for some reason, that still cannot be disclosed?

Agree, it's also just a USB device, so no special trickery with DMA,
shared buffers, etc.

I mean, yeah, the RNDIS code is really old and almost certainly has a
severe lack of input validation, but that still doesn't mean it's
fundamentally impossible.

johannes