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From: Frederic Weisbecker <frederic@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	syzbot+55acd54b57bb4b3840a4@syzkaller.appspotmail.com
Subject: Re: [patch 1/6] posix-cpu-timers: Always clear head pointer on dequeue
Date: Thu, 5 Sep 2019 17:49:35 +0200	[thread overview]
Message-ID: <20190905154934.GD18251@lenoir> (raw)
In-Reply-To: <20190905120539.707986830@linutronix.de>

On Thu, Sep 05, 2019 at 02:03:40PM +0200, Thomas Gleixner wrote:
> The head pointer in struct cpu_timer is checked to be NULL in
> posix_cpu_timer_del() when the delete raced with the exit cleanup. The
> works correctly as long as the timer is actually dequeued via
> posix_cpu_timers_exit*().
> 
> But if the timer was dequeued due to expiry the head pointer is still set
> and triggers the warning.
> 
> In fact keeping the head pointer around after any dequeue is pointless as
> is has no meaning at all after that.
> 
> Clear the head pointer always on dequeue and remove the unused requeue
> function while at it.
> 
> Fixes: 60bda037f1dd ("posix-cpu-timers: Utilize timerqueue for storage")
> Reported-by: syzbot+55acd54b57bb4b3840a4@syzkaller.appspotmail.com
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Reviewed-by: Frederic Weisbecker <frederic@kernel.org>

  reply	other threads:[~2019-09-05 15:49 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-05 12:03 [patch 0/6] posix-cpu-timers: Fallout fixes and permission tightening Thomas Gleixner
2019-09-05 12:03 ` [patch 1/6] posix-cpu-timers: Always clear head pointer on dequeue Thomas Gleixner
2019-09-05 15:49   ` Frederic Weisbecker [this message]
2019-09-05 12:03 ` [patch 2/6] posix-cpu-timers: Fix permission check regression Thomas Gleixner
2019-09-05 17:31   ` Frederic Weisbecker
2019-09-05 18:55     ` Thomas Gleixner
2019-09-05 21:15       ` [patch V2 " Thomas Gleixner
2019-09-09 15:13         ` Frederic Weisbecker
2019-09-10 11:18         ` [tip: timers/core] " tip-bot2 for Thomas Gleixner
2019-09-05 12:03 ` [patch 3/6] posix-cpu-timers: Restrict timer_create() permissions Thomas Gleixner
2019-09-21  0:44   ` Frederic Weisbecker
2019-09-05 12:03 ` [patch 4/6] posix-cpu-timers: Restrict clock_gettime() permissions Thomas Gleixner
2019-09-23 13:39   ` Frederic Weisbecker
2019-09-05 12:03 ` [patch 5/6] posix-cpu-timers: Sanitize thread clock permissions Thomas Gleixner
2019-09-05 12:21   ` Peter Zijlstra
2019-09-05 14:11     ` Thomas Gleixner
2019-09-23 14:03   ` Frederic Weisbecker
2019-09-05 12:03 ` [patch 6/6] posix-cpu-timers: Make PID=0 and PID=self handling consistent Thomas Gleixner
2019-09-23 14:13   ` Frederic Weisbecker
2019-09-23 14:17     ` Thomas Gleixner
2019-09-05 14:48 ` [patch 0/6] posix-cpu-timers: Fallout fixes and permission tightening Frederic Weisbecker
2019-09-05 14:57   ` Thomas Gleixner
2019-09-05 15:21     ` Frederic Weisbecker
2019-09-05 20:32 ` Kees Cook
2019-09-05 21:13   ` Thomas Gleixner

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