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Date: Mon, 11 Apr 2011 22:19:11 -0400
From: Dan Rosenberg <dan.j.rosenberg@...il.com>
To: oss-security@...ts.openwall.com
Cc: "Steven M. Christey" <coley@...-smtp.mitre.org>, Josh Bressers <bressers@...hat.com>, 
	Eugene Teo <eugene@...hat.com>
Subject: Re: CVE request: kernel: multiple issues in ROSE

Any update on this?

-Dan

On Tue, Apr 5, 2011 at 11:37 AM, Dan Rosenberg
<dan.j.rosenberg@...il.com> wrote:
> Hi,
>
> This breakdown seems to make sense.  I'll do my best to break up the
> issues below.
>
>>
>> Dan, could you confirm that this breakdown makes sense?
>>
>> 1) buffer overflows (not validating length is <= the maximum)
>>
>
> 1) When parsing the FAC_NATIONAL_DIGIS facilities field, it's possible
> for a remote host to provide more digipeaters than expected, resulting
> in heap corruption.  Check against ROSE_MAX_DIGIS to prevent
> overflows, and abort facilities parsing on failure.  It looks like
> this will be CVE-2011-1493.
>
> 2) When parsing the FAC_CCITT_DEST_NSAP and FAC_CCITT_SRC_NSAP
> facilities fields, a remote host can provide a length of greater than
> 20, resulting in a stack overflow of the callsign array.
>
>> 2) use of negative signed integers in memcpy() and other operations where
>>   conversion creates a large unsigned integer, referred to as
>>   "underflow"
>>
>
> 3) When parsing the FAC_CCITT_DEST_NSAP and FAC_CCITT_SRC_NSAP
> facilities fields, a remote host can provide a length
> of less than 10, resulting in an underflow in a memcpy size, causing a
> kernel panic due to massive heap corruption.
>
> Note that 2) and 3) are solved by validating a single length field, so
> maybe they should be grouped together?  The above three issues were
> all found by me.
>
>> 3) any other types of problems that aren't covered by those two?  (The
>>   length validation checks don't always have enough context in the source
>>   code).
>>
>
> 4) Ben Hutchings' fixes addressed multiple cases where the ROSE
> protocol did not ensure that socket data being parsed wasn't being
> read in from beyond the boundaries of the incoming socket buffer.  For
> example, a received packet might provide a length field longer than
> the amount of remaining data in the socket buffer.
>
> Looking at the patch, it doesn't appear that any memory corruption
> would be caused by this, since the out-of-bounds data is still
> validated by the parsing code.  I'd say the impact is likely limited
> to possible information disclosure, if the contents of the
> out-of-bounds memory could be inferred by the behavior of the protocol
> during parsing.  It's theoretically possible (but very unlikely) that
> this could cause read accesses to unmapped memory, which would cause a
> DOS.
>
> -Dan
>
>> We would need separate CVE's for the issues found by Dan versus the issues
>> found by Ben Hutchings.
>>
>> Arguably, #2 could probably be broken down further, but without enough
>> source code context in the patches, it's not immediately clear.
>>
>> - Steve
>>
>

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