From: Oleg Nesterov <oleg@redhat.com>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
syzkaller <syzkaller@googlegroups.com>
Subject: Re: perf: use-after-free in perf_release
Date: Tue, 7 Mar 2017 17:51:32 +0100 [thread overview]
Message-ID: <20170307165131.GA6097@redhat.com> (raw)
In-Reply-To: <CACT4Y+bzNOrMHmfP_cv3Jzaqs0zB3qHY9eu0y4JdKvVw0mgveA@mail.gmail.com>
On 03/07, Dmitry Vyukov wrote:
>
> On Tue, Mar 7, 2017 at 3:04 PM, Oleg Nesterov <oleg@redhat.com> wrote:
> > On 03/06, Peter Zijlstra wrote:
> >>
> >> and this is a failed fork().
> >>
> >>
> >> However, inherited events don't have a filedesc to fput(), and
> >> similarly, a task that fails for has never been visible to attach a perf
> >> event to because it never hits the pid-hash.
> >
> > Yes, it is not visible to find_task_by_vpid() until copy_process() does
> > attach_pid(PIDTYPE_PID), and copy_process() can't fail after that.
>
>
> I would what is that that is failed in copy_process. Could it be
> perf_event_init_task itself? Maybe it leaves a pointer to p in some
> shared state on some error conditions?
I am looking at perf_event_init_task() too and I can't understand the
error handling...
perf_event_init_context() can return success even if inherit_task_group() in
the first list_for_each_entry(pinned_groups) fails, "ret" will be overwritten
by the 2nd list_for_each_entry(flexible_groups) loop. "inherited_all" should
be cleared, still this looks confusing at least.
inherit_event() returns NULL under is_orphaned_event() check, not ERR_PTR().
Is it correct?
Oleg.
next prev parent reply other threads:[~2017-03-07 17:45 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-06 9:57 perf: use-after-free in perf_release Dmitry Vyukov
2017-03-06 12:13 ` Peter Zijlstra
2017-03-06 12:17 ` Dmitry Vyukov
2017-03-06 12:23 ` Peter Zijlstra
2017-03-06 12:27 ` Dmitry Vyukov
2017-03-06 12:47 ` Peter Zijlstra
2017-03-06 13:14 ` Peter Zijlstra
2017-03-06 13:34 ` Dmitry Vyukov
2017-03-07 9:08 ` Peter Zijlstra
2017-03-07 9:26 ` Dmitry Vyukov
2017-03-07 9:37 ` Peter Zijlstra
2017-03-07 9:43 ` Dmitry Vyukov
2017-03-07 10:00 ` Peter Zijlstra
2017-03-07 13:16 ` Peter Zijlstra
2017-03-07 13:27 ` Peter Zijlstra
2017-03-07 14:04 ` Oleg Nesterov
2017-03-07 14:17 ` Dmitry Vyukov
2017-03-07 16:51 ` Oleg Nesterov [this message]
2017-03-07 17:29 ` Peter Zijlstra
2017-03-14 12:55 ` Peter Zijlstra
2017-03-14 13:24 ` Oleg Nesterov
2017-03-14 13:47 ` Peter Zijlstra
2017-03-14 14:03 ` Oleg Nesterov
2017-03-14 14:07 ` Peter Zijlstra
2017-03-14 14:30 ` Oleg Nesterov
2017-03-14 15:02 ` Peter Zijlstra
2017-03-14 15:07 ` Peter Zijlstra
2017-03-14 15:37 ` Oleg Nesterov
2017-03-14 15:46 ` Peter Zijlstra
2017-03-14 15:19 ` Oleg Nesterov
2017-03-14 15:26 ` Peter Zijlstra
2017-03-14 15:59 ` Peter Zijlstra
2017-03-15 16:43 ` Oleg Nesterov
2017-03-16 12:05 ` Peter Zijlstra
2017-03-16 13:57 ` Peter Zijlstra
2017-03-16 16:41 ` Oleg Nesterov
2017-03-16 12:47 [PATCH 0/4] perf patches Peter Zijlstra
2017-03-16 12:47 ` [PATCH 1/4] perf: Fix use-after-free in perf_release() Peter Zijlstra
2017-03-16 15:19 ` [tip:perf/urgent] perf/core: " tip-bot for Peter Zijlstra
2017-03-16 12:47 ` [PATCH 2/4] perf: Fix event inheritance on fork() Peter Zijlstra
2017-03-16 15:19 ` [tip:perf/urgent] perf/core: " tip-bot for Peter Zijlstra
2017-03-16 12:47 ` [PATCH 3/4] perf: Simplify perf_event_free_task() Peter Zijlstra
2017-03-16 15:20 ` [tip:perf/urgent] perf/core: " tip-bot for Peter Zijlstra
2017-03-16 12:47 ` [PATCH 4/4] perf: Better explain the inherit magic Peter Zijlstra
2017-03-16 15:21 ` [tip:perf/urgent] perf/core: " tip-bot for Peter Zijlstra
2017-03-16 13:20 ` [PATCH 0/4] perf patches Ingo Molnar
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