Re: [PATCH] exec: fix the racy usage of fs_struct->in_exec

[Christian Brauner]

On Tue, Mar 25, 2025 at 02:21:36PM +0100, Oleg Nesterov wrote:
> On 03/25, Mateusz Guzik wrote:
> >
> > On Tue, Mar 25, 2025 at 11:10 AM Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> > >
> > > On 03/24, Mateusz Guzik wrote:
> > > >
> > > > On Mon, Mar 24, 2025 at 7:28 PM Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> > > > >
> > > > > So to me it would be better to have the trivial fix for stable,
> > > > > exactly because it is trivially backportable. Then cleanup/simplify
> > > > > this logic on top of it.
> > > >
> > > > So I got myself a crap testcase with a CLONE_FS'ed task which can
> > > > execve and sanity-checked that suid is indeed not honored as expected.
> > >
> > > So you mean my patch can't fix the problem?
> >
> > No, I think the patch works.
> >
> > I am saying the current scheme is avoidably hard to reason about.
> 
> Ah, OK, thanks. Then I still think it makes more sense to do the
> cleanups you propose on top of this fix.

I agree. We should go with Oleg's fix that in the old scheme and use
that. And then @Mateusz your cleanup should please go on top!