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References: <1239466586-29410-1-git-send-email-tom.leiming@gmail.com>
	 <20090413163101.GD32368@kroah.com>
Date: Mon, 13 Apr 2009 19:37:47 +0300
Message-ID: <84144f020904130937w4443ed2fjc5645824fd1377f@mail.gmail.com>
Subject: Re: [PATCH] kobject: kzfree object in _release function
From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Greg KH <greg@kroah.com>
Cc: tom.leiming@gmail.com, linux-kernel@vger.kernel.org
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Hi Greg,

On Mon, Apr 13, 2009 at 7:31 PM, Greg KH <greg@kroah.com> wrote:
> On Sun, Apr 12, 2009 at 12:16:26AM +0800, tom.leiming@gmail.com wrote:
>> From: Ming Lei <tom.leiming@gmail.com>
>>
>> It helps to troubleshoot the __buggy__ case, in which
>> unreferenced objects are still accessed, using kzfree
>> to free objects safely in _release function.
>>
>> Signed-off-by: Ming Lei <tom.leiming@gmail.com>
>> ---
>> ?lib/kobject.c | ? ?4 ++--
>> ?1 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib/kobject.c b/lib/kobject.c
>> index a6dec32..cb5a562 100644
>> --- a/lib/kobject.c
>> +++ b/lib/kobject.c
>> @@ -597,7 +597,7 @@ void kobject_put(struct kobject *kobj)
>> ?static void dynamic_kobj_release(struct kobject *kobj)
>> ?{
>> ? ? ? pr_debug("kobject: (%p): %s\n", kobj, __func__);
>> - ? ? kfree(kobj);
>> + ? ? kzfree(kobj);
>> ?}
>>
>> ?static struct kobj_type dynamic_kobj_ktype = {
>> @@ -762,7 +762,7 @@ static void kset_release(struct kobject *kobj)
>> ? ? ? struct kset *kset = container_of(kobj, struct kset, kobj);
>> ? ? ? pr_debug("kobject: '%s' (%p): %s\n",
>> ? ? ? ? ? ? ? ?kobject_name(kobj), kobj, __func__);
>> - ? ? kfree(kset);
>> + ? ? kzfree(kset);
>
>
> What about slab-poisoning? ?Shouldn't we just rely on that instead?

Yes, you should. kzfree() strictly for cases where _correctness_ of
the program requires it (i.e. security concerns).
--
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