Messages in this thread | | | Date | Tue, 03 Apr 2012 14:08:17 +0200 | From | Daniel Lezcano <> | Subject | Re: [PATCH] cpuidle: Avoid possible NULL pointer dereference in __cpuidle_register_device() |
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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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