Re: Re: [PATCH] driver-core: Fix null reference in subsys_interface_unregister

Re: Re: [PATCH] driver-core: Fix null reference in subsys_interface_unregister

[최종환]

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Greg KH wrote:

>On Sat, Jan 14, 2012 at 11:06:03AM +0900, jhbird.choi@samsung.com wrote:
>> From: Jonghwan Choi 
> >
> >Check if the sif is not NULL before de-referencing it

>Why would it be?  Have you hit this somehow?  If so, in what code?

> thanks,

> greg k-h


diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 99dc592..4ddb38b 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -1193,13 +1193,15 @@ EXPORT_SYMBOL_GPL(subsys_interface_register);

 void subsys_interface_unregister(struct subsys_interface *sif)
 {
-       struct bus_type *subsys = sif->subsys;   // -> Sif is already used, that means sif is not null
+       struct bus_type *subsys;
        struct subsys_dev_iter iter;
        struct device *dev;

-       if (!sif)  // -> Check whether sif is null 
+       if (!sif || !sif->subsys)
                return;

+       subsys = sif->subsys;
+
        mutex_lock(&subsys->p->mutex);
        list_del_init(&sif->node);
        if (sif->remove_dev) {
-- 

sif is already used, but  null pointer check for sif later.
so i think that sif should be checked before use it.


Sorry about that, since my e-mail client has a problem,
 I couldn't send that to mailing list. I will send it to mailing list.
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Re: Re: [PATCH] driver-core: Fix null reference in subsys_interface_unregister

[Greg KH]

On Tue, Jan 17, 2012 at 12:35:35AM +0000, 최종환 wrote:
> Greg KH wrote:
> 
> >On Sat, Jan 14, 2012 at 11:06:03AM +0900, jhbird.choi@samsung.com wrote:
> >> From: Jonghwan Choi 
> > >
> > >Check if the sif is not NULL before de-referencing it
> 
> >Why would it be?  Have you hit this somehow?  If so, in what code?
> 
> > thanks,
> 
> > greg k-h
> 
> 
> diff --git a/drivers/base/bus.c b/drivers/base/bus.c
> index 99dc592..4ddb38b 100644
> --- a/drivers/base/bus.c
> +++ b/drivers/base/bus.c
> @@ -1193,13 +1193,15 @@ EXPORT_SYMBOL_GPL(subsys_interface_register);
> 
>  void subsys_interface_unregister(struct subsys_interface *sif)
>  {
> -       struct bus_type *subsys = sif->subsys;   // -> Sif is already used, that means sif is not null
> +       struct bus_type *subsys;
>         struct subsys_dev_iter iter;
>         struct device *dev;
> 
> -       if (!sif)  // -> Check whether sif is null 
> +       if (!sif || !sif->subsys)
>                 return;
> 
> +       subsys = sif->subsys;
> +
>         mutex_lock(&subsys->p->mutex);
>         list_del_init(&sif->node);
>         if (sif->remove_dev) {
> -- 
> 
> sif is already used, but  null pointer check for sif later.
> so i think that sif should be checked before use it.

Yes, you are right, I missed the previous usage.  I'll queue this up for
3.4.

thanks,

greg k-h