linux-kernel - Re: Re: [PATCH] driver-core: Fix null reference in subsys_interface

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Date:	Tue, 17 Jan 2012 00:35:36 +0000 (GMT)
From:	최종환 <jhbird.choi@...sung.com>
To:	Greg KH <gregkh@...e.de>,
	최종환 <jhbird.choi@...sung.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	김국진 <kgene.kim@...sung.com>
Subject: Re: Re: [PATCH] driver-core: Fix null reference in
 subsys_interface_unregister

Greg KH wrote:

>On Sat, Jan 14, 2012 at 11:06:03AM +0900, jhbird.choi@...sung.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.
 Thanks.