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Date: Fri, 5 May 2017 11:52:49 +0200
From: Florian Weimer <fweimer@...hat.com>
To: oss-security@...ts.openwall.com
Subject: Re: rpcbomb: remote rpcbind denial-of-service

On 05/05/2017 11:22 AM, Marcus Meissner wrote:
> On Wed, May 03, 2017 at 05:55:20PM -0700, Seth Arnold wrote:
>> On Wed, May 03, 2017 at 08:55:23PM +0200, Guido Vranken wrote:
>>> This vulnerability allows an attacker to allocate any amount of bytes
>>> (up to 4 gigabytes per attack) on a remote rpcbind host, and the
>>> memory is never freed unless the process crashes or the administrator
>>> halts or restarts the rpcbind service.
>>> [...]
>>> An extensive write-up can be found here:
>>> https://guidovranken.wordpress.com/2017/05/03/rpcbomb-remote-rpcbind-denial-of-service-patches/
>>>
>>> Exploit + patches: https://github.com/guidovranken/rpcbomb/
>>
>> Hello Guido, nice find. Have CVE numbers been requested for this issue
>> yet? Have you investigated if ntirpc is affected too? Much of the code
>> looks similar:
>>
>> http://sources.debian.net/src/ntirpc/1.4.3-3/src/rpc_generic.c/#L728
> 
> We also saw glibc affected.
> 
> https://bugzilla.suse.com/show_bug.cgi?id=1037559#c7
> 
> That said, your reproducer allocates virtual memory, and on systems with overcommit
> there is only neglible impact on overall memory pressure.
> 
> The rpc service will however likely crash at some point though when there is no virtual
> address space left for it.

Thanks, I filed it upstream as well:

https://sourceware.org/bugzilla/show_bug.cgi?id=21461

Looks like both xdr_bytes and xdr_string have a similar bug.

I'd appreciate some guidance on reusing or not reusing CVE IDs here.

Florian

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