From: Al Viro <viro@zeniv.linux.org.uk>
To: Waiman Long <longman@redhat.com>
Cc: Christian Brauner <brauner@kernel.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jens Axboe <axboe@kernel.dk>, Alexey Gladkov <legion@kernel.org>,
David Hildenbrand <david@redhat.com>,
Jann Horn <jannh@google.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] copy_process(): Move fd_install() out of sighand->siglock critical section
Date: Tue, 8 Feb 2022 18:16:41 +0000 [thread overview]
Message-ID: <YgKziblMKsmHkP4f@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <20220208163912.1084752-1-longman@redhat.com>
On Tue, Feb 08, 2022 at 11:39:12AM -0500, Waiman Long wrote:
> One way to solve this problem is to move the fd_install() call out of
> the sighand->siglock critical section.
>
> Before commit 6fd2fe494b17 ("copy_process(): don't use ksys_close()
> on cleanups"), the pidfd installation was done without holding both
> the task_list lock and the sighand->siglock. Obviously, holding these
> two locks are not really needed to protect the fd_install() call.
> So move the fd_install() call down to after the releases of both locks.
Umm... That assumes we can delay it that far. IOW, that nothing
relies upon having pidfd observable in /proc/*/fd as soon as the child
becomes visible there in the first place.
What warranties are expected from CLONE_PIDFD wrt observation of
child's descriptor table?
next prev parent reply other threads:[~2022-02-08 18:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-08 16:39 [PATCH] copy_process(): Move fd_install() out of sighand->siglock critical section Waiman Long
2022-02-08 18:16 ` Al Viro [this message]
2022-02-08 18:51 ` Waiman Long
2022-02-08 19:07 ` Al Viro
2022-02-08 21:59 ` Eric W. Biederman
2022-02-08 22:16 ` Al Viro
2022-02-08 22:25 ` Eric W. Biederman
2022-02-09 16:25 ` Waiman Long
2022-02-11 8:27 ` Christian Brauner
2022-02-09 22:18 ` Eric W. Biederman
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