From: Linus Torvalds <torvalds@linux-foundation.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Eugene Syromiatnikov <esyr@redhat.com>,
Jan Kratochvil <jan.kratochvil@redhat.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Pedro Alves <palves@redhat.com>,
Simon Marchi <simon.marchi@efficios.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RESEND2] ptrace: make ptrace() fail if the tracee changed its pid unexpectedly
Date: Tue, 11 May 2021 10:28:13 -0700 [thread overview]
Message-ID: <CAHk-=whLqbTNc1T+rHCm-kxbVAuhK3hjo5fOgDVf5-z--x1mvQ@mail.gmail.com> (raw)
In-Reply-To: <20210511165626.GA13720@redhat.com>
On Tue, May 11, 2021 at 9:56 AM Oleg Nesterov <oleg@redhat.com> wrote:
>
> This patch makes ptrace() fail in this case until debugger does wait()
> and consumes PTHREAD_EVENT_EXEC which reports old_pid.
I'm ok with the patch, just wondering which way it's supposed to come
to me. Should I just apply it directly?
That said, why this:
> + rcu_read_lock();
> + pid = task_pid_nr_ns(task, task_active_pid_ns(task->parent));
> + rcu_read_unlock();
I don't see why the RCU read lock would be needed? task_pid_nr_ns()
does any required locking itself, afaik.
And even if it wasn't, this all happens with siglock held, can
anything actually change.
Linus
next prev parent reply other threads:[~2021-05-11 17:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 16:56 [PATCH RESEND2] ptrace: make ptrace() fail if the tracee changed its pid unexpectedly Oleg Nesterov
2021-05-11 17:28 ` Linus Torvalds [this message]
2021-05-11 17:53 ` Oleg Nesterov
2021-05-11 18:06 ` Oleg Nesterov
2021-05-12 13:36 ` Oleg Nesterov
2021-05-12 13:56 ` Mathieu Desnoyers
2021-05-12 14:38 ` Oleg Nesterov
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