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From:   Rodrigo Campos <rodrigo@kinvolk.io>
Date:   Sat, 29 May 2021 00:31:55 +0200
Message-ID: <CACaBj2aM0FxsTSeCDu+3tfdBY9-rbPaLA88YW3Fg-ZQDJRGoXQ@mail.gmail.com>
Subject: Re: [PATCH v2 2/4] seccomp: Refactor notification handler to prepare
 for new semantics
To:     Kees Cook <keescook@chromium.org>
Cc:     Sargun Dhillon <sargun@sargun.me>,
        LKML <linux-kernel@vger.kernel.org>, containers@lists.linux.dev,
        Tycho Andersen <tycho@tycho.pizza>,
        Andy Lutomirski <luto@kernel.org>,
        =?UTF-8?Q?Mauricio_V=C3=A1squez_Bernal?= <mauricio@kinvolk.io>,
        Giuseppe Scrivano <gscrivan@redhat.com>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        =?UTF-8?B?TWlja2HDq2wgU2FsYcO8bg==?= <mic@linux.microsoft.com>
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On Fri, May 28, 2021 at 7:14 PM Kees Cook <keescook@chromium.org> wrote:
>
> On Fri, May 28, 2021 at 05:27:39PM +0200, Rodrigo Campos wrote:
> > On Thu, May 27, 2021 at 8:42 PM Kees Cook <keescook@chromium.org> wrote:
> > >
> > > On Thu, May 27, 2021 at 01:51:13PM +0200, Rodrigo Campos wrote:
> > > >
> > > > Kees, as I mentioned in the linked thread, this issue is present in
> > > > 5.9+ kernels. Should we add the cc to stable for this patch? Or should
> > > > we cc to stable the one linked, that just fixes the issue without
> > > > semantic changes to userspace?
> > >
> > > It sounds like the problem is with Go, using addfd, on 5.9-5.13 kernels,
> > > yes?
> >
> > Yes.
> >
> > > Would the semantic change be a problem there? (i.e. it sounds like
> > > the semantic change was fine for the 5.14+ kernels, so I'm assuming it's
> > > fine for earlier ones too.)
> >
> > No, I don't think it will cause any problem.
> >
> > > > Just to be clear, the other patch that fixes the problem without
> > > > userspace visible changes is this:
> > > > https://lore.kernel.org/lkml/20210413160151.3301-1-rodrigo@kinvolk.io/
> > >
> > > I'd prefer to use the now-in-next fix if we can. Is it possible to build
> > > a test case that triggers the race so we can have some certainty that
> > > any fix in -stable covers it appropriately?
> >
> > I've verified that Sargun's patch also solves the problem in mainline.
> > I have now also verified that it applies cleany and fixes the issue
> > for linux-stable/5.10.y and linux-stable/5.12.y too (without the patch
> > I see the problem, with the patch I don't see it).  5.11 is already
> > EOL, so I didn't try it (probably will work as well).
>
> Oh, btw, may I add a Tested-by: from you for this fix?

Oh, right! Yes. Here it goes so it's simpler to add :)

Tested-by: Rodrigo Campos <rodrigo@kinvolk.io>


Thanks!