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To: Julia Lawall <julia.lawall@lip6.fr>
Subject: Re: [patch 00/16] timers: Plug debugobject leaks and use  =?UTF-8?Q?del=5Ftimer=5Fsync=28=29=20in=20exit/teardown?=
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Date: Mon, 24 Mar 2014 10:03:57 +0100
From: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
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On 2014-03-24 08:29, Julia Lawall wrote:
>> Another thing I saw is
>>
>> 	del_timer(&bla->timer);
>> 	....
>> 	kfree(&bla);
>
> In one case I saw the following:
>
>         if (isac->dch.timer.function != NULL) {
>                 del_timer(&isac->dch.timer);
>                 isac->dch.timer.function = NULL;
>         }
>         kfree(isac->mon_rx);
>         isac->mon_rx = NULL;
>
> Is the assignment isac->dch.timer.function = NULL good enough to 
> solve
> the problem?

No. It might lead to a NULL dereference when the other core wants
to call the callback. Same situation as in the other picture.

Thanks,

        tglx