From: Eugene Syromiatnikov <esyr@redhat.com>
To: Christian Brauner <christian.brauner@ubuntu.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
"Dmitry V. Levin" <ldv@altlinux.org>,
Eric Biederman <ebiederm@xmission.com>
Subject: Re: [PATCH v2] fork: check exit_signal passed in clone3() call
Date: Wed, 11 Sep 2019 15:32:13 +0100 [thread overview]
Message-ID: <20190911143213.GB21600@asgard.redhat.com> (raw)
In-Reply-To: <20190911141635.lafrcjwvbhjm3ezy@wittgenstein>
On Wed, Sep 11, 2019 at 04:16:36PM +0200, Christian Brauner wrote:
> On Wed, Sep 11, 2019 at 03:52:36PM +0200, Christian Brauner wrote:
> > On Wed, Sep 11, 2019 at 06:48:52AM -0700, Andrew Morton wrote:
> > > What are the user-visible runtime effects of this bug?
The userspace can set -1 as an exit_signal, and that will break process
signalling and reaping.
> > > Relatedly, should this fix be backported into -stable kernels? If so, why?
> >
> > No, as I said in my other mail clone3() is not in any released kernel
> > yet. clone3() is going to be released in v5.3.
>
> Sigh, I spoke to soon... Hm, this is placed in _do_fork(). There's a
> chance that this might be visible in legacy clone if anyone passes in an
> invalid signal greater than NSIG right now somehow, they'd now get
> EINVAL if I'm seeing this right.
>
> So an alternative might be to only fix this in clone3() only right now
> and get this patch into 5.3 to not release clone3() with this bug from
> legacy clone duplicated.
> And we defer the actual legacy clone fix until after next merge window
> having it stew in linux-next for a couple of rcs. Distros often pull in
> rcs so if anyone notices a regression for legacy clone we'll know about
> it... valid_signal() checks at process exit time when the parent is
> supposed to be notifed will catch faulty signals anyway so it's not that
> big of a deal.
As the patch is written, only copy_clone_args_from_user is touched (which
is used only by clone3 and not legacy clone), and the check added
replicates legacy clone behaviour: userspace can set 0..CSIGNAL
as an exit_signal. Having ability to set exit_signal in NSIG..CSIGNAL
renge seems to be a bug, but at least it seems to be harmless one
and indeed may be addressed separately in the future.
next prev parent reply other threads:[~2019-09-11 14:32 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-10 17:58 [PATCH v2] fork: check exit_signal passed in clone3() call Eugene Syromiatnikov
2019-09-11 13:31 ` Oleg Nesterov
2019-09-11 13:47 ` Christian Brauner
2019-09-11 13:48 ` Andrew Morton
2019-09-11 13:52 ` Christian Brauner
2019-09-11 14:16 ` Christian Brauner
2019-09-11 14:32 ` Eugene Syromiatnikov [this message]
2019-09-11 14:54 ` Christian Brauner
2019-09-11 15:08 ` Dmitry V. Levin
2019-09-11 15:20 ` Eugene Syromiatnikov
2019-09-11 15:31 ` Christian Brauner
2019-09-13 9:07 ` Christian Brauner
2019-09-11 17:32 ` Eric W. Biederman
-- strict thread matches above, loose matches on Subject: below --
2019-09-10 17:58 Eugene Syromiatnikov
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