Subject: Re: [PATCH] powerpc/kernel: Fix potential spectre v1 in syscall

From: Breno Leitao <[email-masked]>
Date: Tue, 12 Mar 2024 02:05:43 -0700

On Tue, Mar 12, 2024 at 08:17:42AM +0000, Christophe Leroy wrote:
> +Nathan as this is RTAS related.
> 
> Le 21/08/2018 à 20:42, Breno Leitao a écrit :
> > The rtas syscall reads a value from a user-provided structure and uses it
> > to index an array, being a possible area for a potential spectre v1 attack.
> > This is the code that exposes this problem.
> > 
> > 	args.rets = &args.args[nargs];
> > 
> > The nargs is an user provided value, and the below code is an example where
> > the 'nargs' value would be set to XX.
> > 
> > 	struct rtas_args ra;
> > 	ra.nargs = htobe32(XX);
> > 	syscall(__NR_rtas, &ra);
> 
> 
> This patch has been hanging around in patchwork since 2018 and doesn't 
> apply anymore. Is it still relevant ? If so, can you rebase et resubmit ?

This seems to be important, since nargs is a user-provided value. I can
submit it if the maintainers are willing to accept. I do not want to
spend my time if no one is willing to review it.

Thanks for revamping this one.