[lkml]   [2012]   [Apr]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] cpuidle: Avoid possible NULL pointer dereference in __cpuidle_register_device()
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<>
>>> ---
>> 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 :)

-- Daniel

<> │ Open source software for ARM SoCs

Follow Linaro: <> Facebook |
<!/linaroorg> Twitter |
<> Blog
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2012-04-03 14:11    [from the cache]
©2003-2014 Jasper Spaans. hosted at Digital Ocean