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

[Kees Cook]

On March 25, 2025 7:46:15 AM PDT, Christian Brauner <brauner@xxxxxxxxxx> wrote:
>On Tue, Mar 25, 2025 at 03:15:06PM +0100, Mateusz Guzik wrote:
>> On Tue, Mar 25, 2025 at 2:30 PM Christian Brauner <brauner@xxxxxxxxxx> wrote:
>> >
>> > 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!
>> 
>> Ok, in that case I'm gonna ship when I'm gonna ship(tm), maybe later this week.
>
>Ok, I've taken the patch as I've got a first round of fixes to send
>already.

Thanks! 

Acked-by: Kees Cook <kees@xxxxxxxxxx>


-- 
Kees Cook