Re: CVE request: Linux kernel mbcache lock contention denial of service.

[Greg KH <greg () kroah com>]

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