Re: [PATCH 2/2] driver core: add TAINT_FORCED_BIND for when userspace manually messes with devices and drivers

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Aug 26, 2026 at 12:58:00PM +0100, Bradley Morgan wrote:
> On 26 August 2026 10:19:33 BST, Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >The ability to add and remove devices from a driver through the sysfs
> >"bind" and "unbind" files was created all those decades ago as a way
> >that kernel developers can iterate faster, and provide a debugging way
> >for users to attempt to add a new device to a driver without having to
> >rebuild their kernel.
> >
> >This api over the years has been abused and recently come under a major
> >fuzzing "attack" through tools like syzbot which decided that it would
> >attempt to just randomly bind any driver to any type of device, causing
> >loads of unneeded errors and pointless kernel patches to be generated by
> >unsuspecting new developers.
> >
> >Handle all of this by adding a new taint flag, TAINT_FORCED_BIND, which
> >will be set on the driver if the bind/unbind sysfs files are ever
> >successfully written to.  This lets kernel developers "know" that a user
> >is attempting to do something that is not normal, and as such, if the
> >kernel breaks they get to keep the shiny pieces laying around on the
> >floor.
> >
> >Note, the taint flag gets set _BEFORE_ the bind/unbind callback happens,
> >as many times crashes/oops/warnings/failures happen within the callback,
> >and the taint flag needs to be there to show what was being attempted.
> >If it were to be set after the callback happens, the oops report would
> >not properly reflect what foolishness was being attempted.
> >
> 
> sashiko found a couple valid concerns for 2/2

Yes, will fix that for v2.

thanks,

greg k-h