Re: 7.1 regression bisected to "usb: core: Fix SuperSpeed root hub wMaxPacketSize"

[Michal Pecio <michal.pecio@gmail.com>]

On Thu, 2 Jul 2026 14:22:25 +0200, Greg Kroah-Hartman wrote:
> On Thu, Jul 02, 2026 at 02:20:05PM +0200, Michel Dänzer wrote:
> > That reminded me that I'm using (an older upstream version of)
> > usbguard. Unfortunately its GUI notifications when it blocks a USB
> > device aren't working reliably currently.
> > 
> > Manually firing up its settings app revealed that it was indeed
> > blocking the USB3 hub. Overriding it to be allowed fixed the issue
> > with the bisected commit.
> > 
> > Looks like a false alert after all, sorry for the noise, and thanks
> > for the help.  
> 
> Thanks for letting us know, and this isn't the first time that
> usbguard has caused a problem recently.  Did we change something that
> broke it's functionality?

A few weeks ago we corrected a small inconsistency in USB 3.0 root hub
descriptors to avoid some warnings. That's the bisected patch.

Apparently, usbguard can be configured to reject all devices except for
a list of descriptor hashes. Not sure if there are other whitelisting
options besides hashes? Using this method for root hubs seems to bring
no security benefit (you trust the kernel, right?), only trouble.

Now, these systems require user action to authorize the new descriptor.
Otherwise, usbguard runs amok and disables USB 3.0 root hubs with all
children, AFAIU.

Or is there more to it and the issue is somehow magically specific to
Lenovo USB docks? Both affected users complained about such docks, but
maybe they are simply the only USB devices used by usbguard users :)

Regards,
Michal