linux-kernel - Re: intel_cacheinfo: potential NULL dereference?

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Message-ID: <4C20EE54.2050506@zytor.com>
Date:	Tue, 22 Jun 2010 10:09:40 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Jiri Slaby <jirislaby@...il.com>
CC:	Borislav Petkov <bp@...64.org>, "x86@...nel.org" <x86@...nel.org>,
	Linux kernel mailing list <linux-kernel@...r.kernel.org>
Subject: Re: intel_cacheinfo: potential NULL dereference?

On 06/22/2010 07:11 AM, Jiri Slaby wrote:
> On 06/22/2010 03:08 PM, Borislav Petkov wrote:
>> From: Jiri Slaby <jirislaby@...il.com>
>> Date: Tue, Jun 22, 2010 at 07:20:14AM -0400
>>
>>> On 06/22/2010 01:18 PM, Jiri Slaby wrote:
>>>> Stanse found, that this_leaf->l3 is dereferenced at <<1>>, but checked
>>>> for being NULL at <<2>>. Is the check superfluous or the dev assignment
>>>> should go after the check?
>>>
>>> Oh, and I have another report with same symptoms for show_cache_disable.
>>
>> Right, so I have a patch in tip/x86/cpu
>> (8cc1176e5de534d55cb26ff0cef3fd0d6ad8c3c0) which reorganizes
>> and cleans up that code. With it, all possible checks land in
>> amd_check_l3_disable() and if they have all been passed, the PCI dev is
>> guaranteed to be properly set. So no need for sprinkling additional NULL
>> checks in the code.
>>
>> How's that?
> 
> Looks good.
> 

Do we need a patch for the existing code to go into -linus and -stable,
though?

	-hpa

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