From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
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, 14 Mar 2017 16:46:34 +0100 [thread overview]
Message-ID: <20170314154634.GS5680@worktop> (raw)
In-Reply-To: <20170314153705.GB31766@redhat.com>
On Tue, Mar 14, 2017 at 04:37:05PM +0100, Oleg Nesterov wrote:
> On 03/14, Peter Zijlstra wrote:
> >
> > Do we want a WARN_ON_ONCE(atomic_read(&tsk->usage)); in free_task()?
> > Because in the above scenario we're freeing it with references on.
>
> Not sure, in this case copy_process() should decrement tsk->usage
> before free_task(), note the atomic_set(&tsk->usage, 2) in
> dup_task_struct().
>
> Perhaps we should just add WARN_ON(tsk->usage != 2) into copy_process()
> right before free_task() ?
Sure; that works. I'll try that once I'm back home again, to see if
there's unexpected fail because other things increment it.
next prev parent reply other threads:[~2017-03-14 15:47 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
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 [this message]
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
-- strict thread matches above, loose matches on Subject: below --
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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