Xen.org security team
2013-Feb-05 13:15 UTC
Xen Security Advisory 39 (CVE-2013-0216, CVE-2013-0217) - Linux netback DoS via malicious guest ring.
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Xen Security Advisory CVE-2013-0216,CVE-2013-0217 / XSA-39
version 2
Linux netback DoS via malicious guest ring.
UPDATES IN VERSION 2
===================
Public release.
ISSUE DESCRIPTION
================
The Xen netback implementation contains a couple of flaws which can
allow a guest to cause a DoS in the backend domain, potentially
affecting other domains in the system.
CVE-2013-0216 is a failure to sanity check the ring producer/consumer
pointers which can allow a guest to cause netback to loop for an
extended period preventing other work from occurring.
CVE-2013-0217 is a memory leak on an error path which is guest
triggerable.
IMPACT
=====
A malicious guest can mount a DoS affecting the entire system.
VULNERABLE SYSTEMS
=================
All systems running guests with access to PV network devices are
vulnerable.
CVE-2013-0216 affects both mainline ("pvops") and classic-Xen patch
kernels.
CVE-2013-0217 affects only mainline ("pvops") kernels.
MITIGATION
=========
Running HVM guests with only emulated or passthrough NICs or PV guests
with only passthrough NICs will avoid this vulnerability.
RESOLUTION
=========
Applying the appropriate attached patches in sequence resolves this issue.
xsa39-pvops-*.patch Apply to mainline Linux 3.8-rc2
xsa39-classic-*.patch Apply to linux-2.6.18-xen tree.
All patches for the given branch should be applied in numerical order.
$ sha256sum xsa39*.patch
4b75961673b940f5eb31451080dd668b9119eb88db1df44db1a3ba4b0d037ce1
xsa39-classic-0001-xen-netback-garbage-ring.patch
096143750b99eb2d88970338c3f9debfbbfdaef766525a620281b28528ebe0ce
xsa39-classic-0002-xen-netback-wrap-around.patch
99cf93e37985908243b974cc726f57e592e62ae005eca52969f11fb6fdea6fb5
xsa39-pvops-0001-xen-netback-shutdown-the-ring-if-it-contains-garbage.patch
e0c4226b0910ca455f22ae117e8346d87053e9faf03ec155dd6c31e2f58a1969
xsa39-pvops-0002-xen-netback-don-t-leak-pages-on-failure-in-xen_netbk.patch
70e6cb644a57cdda7f29eb86086a8e697706c3fc974a44c52322e451fd6b9d5c
xsa39-pvops-0003-xen-netback-free-already-allocated-memory-on-failure.patch
5d0db59bbd5ad3a7efae78a6c26fc2491b7c553e5519dd946d1422a116af73dd
xsa39-pvops-0004-netback-correct-netbk_tx_err-to-handle-wrap-around.patch
$
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