oss-security - Re: kernel: [PARISC] led.c - fix potential stack overflow in led_proc

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Message-ID: <4C65FC75.7040108@redhat.com>
Date: Sat, 14 Aug 2010 10:16:21 +0800
From: Eugene Teo <eugene@...hat.com>
To: Ben Hutchings <ben@...adent.org.uk>
CC: oss-security@...ts.openwall.com, dann frazier <dannf@...ian.org>,
        "Steven M. Christey" <coley@...us.mitre.org>
Subject: Re: kernel: [PARISC] led.c - fix potential stack overflow
 in led_proc_write()

On 08/14/2010 09:28 AM, Ben Hutchings wrote:
> On Sat, 2010-08-14 at 09:00 +0800, Eugene Teo wrote:
>> On 08/14/2010 08:54 AM, dann frazier wrote:
>>> On Tue, Aug 03, 2010 at 01:51:15AM -0400, Moritz Muehlenhoff wrote:
>>>> On Tue, Aug 03, 2010 at 11:46:58AM +0800, Eugene Teo wrote:
>>>>> Ilja reported way back in Nov 2007. A writer to /proc/pdc/led(?) can
>>>>> cause the kernel to consume an unbounded amount of stack, and result
>>>>> in stack corruption.
>>>>>
>>>>> http://www.spinics.net/lists/linux-parisc/msg02960.html
>>>>>
>>>>> If you need a CVE name, change the subject to indicate that. We are
>>>>> not requesting one as we do not support the PA-RISC architecture in
>>>>> our distribution.
>>>>
>>>> Debian supports hppa.
>>>>
>>>> Steven, please assign a CVE ID.
>>>
>>> Ben Hutchings pointed out that this file is only writeable by root -
>>> can it therefore be considered a security issue?
>>
>>    From the bug report:
>> "the problem being that the stack is limited and count is not (except
>> for the MAX_INT check done in sys_write() I guess). this could lead to
>> stack corruption (when for example calling capable())."
>
> But the file permissions are checked even before the function is called,
> are they not?

If that's the case with all distros, I would not consider this a 
security issue.

Thanks, Eugene
-- 
main(i) { putchar(182623909 >> (i-1) * 5&31|!!(i<7)<<6) && main(++i); }

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