linux-kernel - Re: old buffer overflow in moxa driver

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Date:	Tue, 01 May 2007 04:29:27 -0400
From:	Andres Salomon <dilinger@...ian.org>
To:	Jiri Slaby <jirislaby@...il.com>
CC:	Alan Cox <alan@...rguk.ukuu.org.uk>, dann frazier <dannf@...com>,
	linux-kernel@...r.kernel.org, support@...a.com.tw
Subject: Re: old buffer overflow in moxa driver

Jiri Slaby wrote:
> Alan Cox napsal(a):
>>>   I noticed that the moxa input checking security bug described by
>>> CVE-2005-0504 appears to remain unfixed upstream.
>>>  
>>> The issue is described here:
>>>   http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-0504
>>>
>>> Debian has been shipping the following patch from Andres Salomon. I
>>> tried contacting the listed maintainer a few months ago but received
>>> no response.
>>
>>        case MOXA_LOAD_BIOS:
>>         case MOXA_FIND_BOARD:
>>         case MOXA_LOAD_C320B:
>>         case MOXA_LOAD_CODE:
>>                 if (!capable(CAP_SYS_RAWIO))
>>                         return -EPERM;
>>                 break;
>>
>> At the point you abuse these calls you can already just load arbitary
>> data from userspace anyway.
> 
> The problem is that we BUG_ON, when len < 0 in copy_from_user which is unlikely
> something we want to cause?
> 
> regards,


Right; the lack of input checking is most definitely a bug.  It's no
longer a security issue, as a CAP_SYS_RAWIO check was added at some
point to the code path, but it's still a bug.
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