From: Daniel Lezcano <daniel.lezcano@linaro.org>
To: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
Cc: lenb@kernel.org, khilman@ti.com, deepthi@linux.vnet.ibm.com,
g.trinabh@gmail.com, arjan@infradead.org,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
amit.kucheria@linaro.org
Subject: Re: [PATCH] cpuidle: Avoid possible NULL pointer dereference in __cpuidle_register_device()
Date: Tue, 03 Apr 2012 14:08:17 +0200 [thread overview]
Message-ID: <4F7AE831.507@linaro.org> (raw)
In-Reply-To: <4F7AE42F.9080800@linux.vnet.ibm.com>
On 04/03/2012 01:51 PM, Srivatsa S. Bhat wrote:
> On 04/03/2012 01:01 AM, Daniel Lezcano wrote:
>
>> On 04/02/2012 04:44 PM, Srivatsa S. Bhat wrote:
>>> In __cpuidle_register_device(), "dev->cpu" is used before checking if
>>> dev is
>>> non-NULL. Fix it.
>>>
>>> Signed-off-by: Srivatsa S. Bhat<srivatsa.bhat@linux.vnet.ibm.com>
>>> ---
>>
>> That should be fixed at the caller level. Usually, static function does
>> not check the function parameters, it is up to the exported function to
>> do that. It is supposed the static functions are called with valid
>> parameters.
>>
>
>
> Ok, good point! I hadn't thought about that.. I just happened to notice
> that in __cpuidle_register_device(), the dev == NULL check is performed
> _after_ dereferencing it, which made the check useless. So I tried to
> fix that within that function. But thanks for pointing out the semantics..
>
>> There are two callers for __cpuidle_register_device:
>> * cpuidle_register_device
>> * cpuidle_enable_device
>>
>> Both of them do not check 'dev' is a valid parameter. They should as
>> they are exported and could be used by an external module. IMHO, BUG_ON
>> could be used here if dev == NULL.
>>
>
>
> BUG_ON? That would crash the system.. which might be unnecessary..
Mmh, yes, I agree. never mind.
> How about checking if dev == NULL in the 2 callers like you suggested
> and returning -EINVAL if dev is indeed NULL?
> (And of course no checks for dev == NULL in __cpuidle_register_device).
Ok for me.
> Thank you for the review!
You are welcome :)
Thanks
-- Daniel
--
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next prev parent reply other threads:[~2012-04-03 12:08 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-02 14:44 [PATCH] cpuidle: Avoid possible NULL pointer dereference in __cpuidle_register_device() Srivatsa S. Bhat
2012-04-02 19:31 ` Daniel Lezcano
2012-04-03 11:51 ` Srivatsa S. Bhat
2012-04-03 12:08 ` Daniel Lezcano [this message]
2012-04-03 13:15 ` Srivatsa S. Bhat
2012-04-03 13:51 ` Daniel Lezcano
2012-04-03 14:04 ` Srivatsa S. Bhat
2012-04-03 14:17 ` Daniel Lezcano
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