Bug 1460170 - (CVE-2017-9524) CVE-2017-9524 Qemu: nbd: segmentation fault due to client non-negotiation
CVE-2017-9524 Qemu: nbd: segmentation fault due to client non-negotiation
Status: NEW
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
unspecified
All Linux
medium Severity medium
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Assigned To: Red Hat Product Security
impact=moderate,public=20170526,repor...
: Security
Depends On: 1451614 1460172 1460173 1460179 1460180 1460181 1460182 1460184 1460185 1460186 1460187 1460188 1460192 1476024
Blocks: 1460107
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Reported: 2017-06-09 06:15 EDT by Prasad J Pandit
Modified: 2018-01-30 19:20 EST (History)
41 users (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Quick Emulator (QEMU) built with Network Block Device (NBD) Server support was vulnerable to a null-pointer dereference issue. The flaw could occur when releasing a client that was not initialized due to failed negotiation. A remote user or process could exploit this flaw to crash the qemu-nbd server (denial of service).
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Description Prasad J Pandit 2017-06-09 06:15:05 EDT
Quick Emulator(Qemu) built with the Network Block Device(NBD) Server support
is vulnerable to a null pointer dereference issue. It could occur while
releasing a client, which was not initialised due to failed negotiation.

A remote user/process could use this flaw to crash the qemu-nbd server
resulting in DoS.

Upstream patch:
---------------
  -> https://lists.gnu.org/archive/html/qemu-devel/2017-05/msg06240.html
  -> https://lists.gnu.org/archive/html/qemu-devel/2017-06/msg02321.html

Reference:
----------
  -> http://www.openwall.com/lists/oss-security/2017/06/12/1
Comment 1 Prasad J Pandit 2017-06-09 06:28:02 EDT
Created xen tracking bugs for this issue:

Affects: fedora-all [bug 1460173]
Comment 2 Prasad J Pandit 2017-06-09 06:28:26 EDT
Created qemu tracking bugs for this issue:

Affects: fedora-all [bug 1460172]
Comment 6 Eric Blake 2017-06-09 07:15:01 EDT
(In reply to Prasad J Pandit from comment #0)
> Quick Emulator(Qemu) built with the Network Block Device(NBD) Server support
> is vulnerable to a null pointer dereference issue. It could occur while
> releasing a client, which was not initialised due to failed negotiation.
> 
> A remote user/process could use this flaw to crash the qemu-nbd server
> resulting in DoS.
> 
> Upstream patch:
> ---------------
>   -> https://lists.gnu.org/archive/html/qemu-devel/2017-05/msg06240.html
>   -> https://lists.gnu.org/archive/html/qemu-devel/2017-06/msg02321.html

The description, while factually correct, is incomplete. The real problem is that qemu-nbd must NOT exit due to a port scan. The fact that it was exiting due to a segmentation fault makes it a little more obvious that the code was buggy, but even if NO null pointer dereference occurred, there is STILL a denial of service if a well-timed port scan is able to cause qemu-nbd to exit prior to an actual client being able to connect.
Comment 10 errata-xmlrpc 2017-07-05 04:16:25 EDT
This issue has been addressed in the following products:

  RHEV 3.X Hypervisor and Agents for RHEL-7
  RHEV 4.X RHEV-H and Agents for RHEL-7

Via RHSA-2017:1682 https://access.redhat.com/errata/RHSA-2017:1682
Comment 11 errata-xmlrpc 2017-07-05 05:47:15 EDT
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2017:1681 https://access.redhat.com/errata/RHSA-2017:1681
Comment 15 errata-xmlrpc 2017-08-01 21:02:41 EDT
This issue has been addressed in the following products:

  Red Hat OpenStack Platform 10.0 (Newton)
  Red Hat OpenStack Platform 11.0 (Ocata)
  Red Hat Enterprise Linux OpenStack Platform 6.0 (Juno) for RHEL 7
  Red Hat Enterprise Linux OpenStack Platform 7.0 (Kilo) for RHEL 7
  Red Hat OpenStack Platform 8.0 (Liberty)
  Red Hat OpenStack Platform 9.0 (Mitaka)

Via RHSA-2017:2408 https://access.redhat.com/errata/RHSA-2017:2408

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