linux-kernel - Re: Out-of-bounds access in get_wchan (arch/x86/kernel/process

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Message-ID: <CACT4Y+Y2-d0TFq=oq-xFt8udrYc0r8_aROdUfVU29KJBhwWpAQ@mail.gmail.com>
Date:	Wed, 11 Sep 2013 22:16:32 +0400
From:	Dmitry Vyukov <dvyukov@...gle.com>
To:	Andi Kleen <ak@...ux.intel.com>, Wolfram Gloger <wg@...loc.de>
Cc:	LKML <linux-kernel@...r.kernel.org>, Paul Turner <pjt@...gle.com>,
	Andrey Konovalov <andreyknvl@...gle.com>,
	Kostya Serebryany <kcc@...gle.com>
Subject: Re: Out-of-bounds access in get_wchan (arch/x86/kernel/process_64.c)

On Wed, Sep 11, 2013 at 2:06 AM, Andi Kleen <ak@...ux.intel.com> wrote:
>> Indeed, get_wchan ensures that fp<stack+THREAD_SIZE, but then dereferences fp+8:
>>
>> 434                 if (fp < (unsigned long)stack ||
>> 435                     fp >= (unsigned long)stack+THREAD_SIZE)
>> 436                         return 0;
>> 437                 ip = *(u64 *)(fp+8);
>>
>> It must check that fp+8<stack+THREAD_SIZE.
>> As far as I see, the bug can lead to garbage return values or in the
>> worst case to crash.
>
> Thanks for the report.
>
> The change looks good to me. Can you please submit a formal signed off patch
> to x86@...nel.org ?

Hi Andi,

Wolfram has a patch for it.
Wolfram, please send your patch to x86@...nel.org.
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