Re: [PATCH 0/4] x86/ibt: Implement FineIBT

[Peter Zijlstra <peterz@infradead.org>]

On Fri, Oct 28, 2022 at 11:01:08AM +0000, David Laight wrote:
> From: Peter Zijlstra
> > Sent: 27 October 2022 10:28
> > 
> > Hi all,
> > 
> > Updated FineIBT series; I've (hopefully) incorporated all feedback from last
> > time with the notable exception of the Kconfig CFI default -- I'm not sure we
> > want to add to the Kconfig space for this, also what would a distro do with it.
> > 
> > Anyway; please have a look, I'm hoping to merge this soonish so we can make the
> > next cycle.
> 
> Is there a test to ensure that modules are actually compiled
> with the required endbra, function prologue gap (etc).
> Having the module load fail is somewhat better than a crash.
> 
> It is almost certainly quite easy to generate an out of tree module that
> is missing all of those (even if compiled at the same time as the kernel).
> (Never mind issues with modules that contain binary blobs.)

There is not; it is always possible to load a 'malformed' module. We
have no sanity checking on modules. It is no different from any other
binary compatilibity issue; if you build a dud module, you get to keep
the pieces.