Re: CVE-2016-5011: util-linux: Extended partition loop in MBR partition table leads to DoS

[Cedric Buissart <cbuissar () redhat com>]

On Mon, Jul 11, 2016 at 12:51 PM, Hanno Böck <hanno () hboeck de> wrote:

> On Mon, 11 Jul 2016 12:11:43 +0200
> Cedric Buissart <cbuissar () redhat com> wrote:
>
> > CVE-2016-5011: util-linux: Extended partition loop in MBR partition
> > table leads to DoS
>
> Have you discovered this bug or do you know how it was discovered?
It was reported to us by Michael Gruhn & Christian Moch

> Was it found with fuzzing or code inspection?
I do not know, there was no info on the discovery method in the report.

> I have done fuzzing on partitioning tools before, however I hadn't
> found anything, this bug indicates I haven't looked enough :-)
I looked at other projects to see what is being done to prevent this
particular loop from happening. Until now, tools I checked are protected
either by detecting the loop (i.e.: actively searching for a relative
offset of 0 for the next EBR, as done by this util-linux patch; partprobe
and fdisk are doing that), or enforcing a limit on the maximum number of
partitions for a device (Linux kernel, kpartx & other tools I currently
checked)

> --
> Hanno Böck
> https://hboeck.de/
>
> mail/jabber: hanno () hboeck de
> GPG: BBB51E42



-- 
Cedric Buissart,
Product Security