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Date: Mon, 5 Sep 2016 15:57:48 +0200
From: Greg KH <greg@...ah.com>
To: oss-security@...ts.openwall.com
Cc: cve-assign@...re.org
Subject: Re: CVE request: Linux kernel mbcache lock contention
 denial of service.

On Mon, Aug 22, 2016 at 03:28:51PM +1000, Wade Mealing wrote:
> Gday,
> 
> A design flaw was found in the file extended attribute handling of the
> linux kernels handling of cached attributes.  Too many entries in the
> cache cause a soft lockup while attempting to iterate the cache and
> access relevant locks.
> 
> Upstream has replaced the mbcache code with an updated version which
> was not a patch but a clear-cut reimplementation of the code, no
> single diff
> 
> Soft lockup information is in both the bugzilla.kernel.org and
> referred to in the LWN article.  This would affect containers running
> with ext4 as it shares the same mbcache between all containers/host.
> 
> This did not affect Red Hat Enterprise Linux versions 5,6 or 7, so I
> can't validate the claim that it does affect other newer kernels.
> This may be worthwhile tracking for others who are affected by this
> flaw.
> 
> For those following along at home, this seemed to be fixed in:
> 
>  ±  git tag --contains be0726d33cb8f411945884664924bed3cb8c70ee
> v4.6

That commit is for only the ext2 filesystem, how would it fix an issue
in ext4?

totally confused,

greg k-h

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