From ${URL} : Xen Security Advisory XSA-89 version 2 HVMOP_set_mem_access is not preemptible UPDATES IN VERSION 2 ==================== Public release. ISSUE DESCRIPTION ================= Processing of the HVMOP_set_mem_access HVM control operations does not check the size of its input and can tie up a physical CPU for extended periods of time. IMPACT ====== In a configuration where device models run with limited privilege (for example, stubdom device models), a guest attacker who successfully finds and exploits an unfixed security flaw in qemu-dm could leverage the other flaw into a Denial of Service affecting the whole host. In the more general case, in more abstract terms: a malicious administrator of a domain privileged with regard to an HVM guest can cause Xen to become unresponsive leading to a Denial of Service. VULNERABLE SYSTEMS ================== All Xen versions from 4.1 onwards are vulnerable. In 4.2 only 64-bit versions of the hypervisor are vulnerable (HVMOP_set_mem_access is not available in 32-bit hypervisors). The vulnerability is only exposed to service domains for HVM guests which have privilege over the guest. In a usual configuration that means only device model emulators (qemu-dm). In the case of HVM guests whose device model is running in an unrestricted dom0 process, qemu-dm already has the ability to cause problems for the whole system. So in that case the vulnerability is not applicable. The situation is more subtle for an HVM guest with a stub qemu-dm. That is, where the device model runs in a separate domain (in the case of xl, as requested by "device_model_stubdomain_override=1" in the xl domain configuration file). The same applies with a qemu-dm in a dom0 process subjected to some kind kernel-based process privilege limitation (eg the chroot technique as found in some versions of XCP/XenServer). In those latter situations this issue means that the extra isolation does not provide as good a defence (against denial of service) as intended. That is the essence of this vulnerability. However, the security is still better than with a qemu-dm running as an unrestricted dom0 process. Therefore users with these configurations should not switch to an unrestricted dom0 qemu-dm. Finally, in a radically disaggregated system: where the HVM service domain software (probably, the device model domain image) is not always supplied by the host administrator, a malicious service domain administrator can excercise this vulnerability. MITIGATION ========== Running only PV guests will avoid this vulnerability. In a radically disaggregated system, restricting HVM service domains to software images approved by the host administrator will avoid the vulnerability. CREDITS ======= This issue was discovered by Jan Beulich. RESOLUTION ========== Applying the appropriate attached patch resolves this issue. xsa89.patch xen-unstable, Xen 4.4.x, Xen 4.3.x, Xen 4.2.x xsa89-4.1.patch Xen 4.1.x $ sha256sum xsa89*.patch 741c8fbbfa8e425d8debba17135d4c2e1e962d15717769bc93d68a65b5dc5ea6 xsa89.patch 7d965e9bf1894b7d909bfaddbc6b7bdcee0ba91b86942ce85e0ae80464f2463e xsa89-4.1.patch $ @maintainer(s): after the bump, in case we need to stabilize the package, please let us know if it is ready for the stabilization or not.
+*xen-4.4.0-r1 (09 Apr 2014) +*xen-4.3.2-r1 (09 Apr 2014) +*xen-4.2.4-r1 (09 Apr 2014) + + 09 Apr 2014; Yixun Lan <dlan@gentoo.org> +xen-4.2.4-r1.ebuild, + +xen-4.3.2-r1.ebuild, +xen-4.4.0-r1.ebuild: + bump stable patches, fix bug #505714, XSA-89
Maintainers, please advise when eBuild has had enough testing and is ready for stabilization. For Versions: +*xen-4.3.2-r1 (09 Apr 2014) +*xen-4.2.4-r1 (09 Apr 2014)
CVE-2014-2599 (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2014-2599): The HVMOP_set_mem_access HVM control operations in Xen 4.1.x for 32-bit and 4.1.x through 4.4.x for 64-bit allow local guest administrators to cause a denial of service (CPU consumption) by leveraging access to certain service domains for HVM guests and a large input.
Is this fixed as part of Bug 500530?
this is already fixed, please see comment #1 of this bug. so, all ebuilds in tree already include this fix, thanks
Arches and Mainter(s), Thank you for your work. Added to an existing GLSA request.
This issue was resolved and addressed in GLSA 201407-03 at http://security.gentoo.org/glsa/glsa-201407-03.xml by GLSA coordinator Mikle Kolyada (Zlogene).
