From ${URL} : Xen Security Advisory XSA-92 version 2 HVMOP_set_mem_type allows invalid P2M entries to be created UPDATES IN VERSION 2 ==================== Public release. ISSUE DESCRIPTION ================= The implementation in Xen of the HVMOP_set_mem_type HVM control operations attempts to exclude transitioning a page from an inappropriate memory type. However, only an inadequate subset of memory types is excluded. There are certain other types that don't correspond to a particular valid page, whose page table translation can be inappropriately changed (by HVMOP_set_mem_type) from not-present (due to the lack of valid memory page) to present. If this occurs, an invalid translation will be established. 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 crash leading to a Denial of Service. Arbitrary code execution, and therefore privilege escalation, cannot be entirely excluded: On a system with a RAM page present immediately below the 52-bit address boundary, this would be possible. However, we are not aware of any systems with such a memory layout. VULNERABLE SYSTEMS ================== All Xen versions from 4.1 onwards are vulnerable. 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 exercise 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. xsa92.patch xen-unstable, Xen 4.4.x, Xen 4.3.x xsa92-4.2.patch Xen 4.2.x xsa92-4.1.patch Xen 4.1.x @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.
bug fixed in versions: xen-4.4.0-r2 xen-4.3.2-r2 xen-4.2.4-r2 xen-tools-4.4.0-r2 xen-tools-4.3.2-r2 xen-tools-4.2.4-r2 ChangeLog: +*xen-4.4.0-r2 (09 May 2014) +*xen-4.3.2-r2 (09 May 2014) +*xen-4.2.4-r2 (09 May 2014) + + 09 May 2014; Yixun Lan <dlan@gentoo.org> -xen-4.2.4.ebuild, + +xen-4.2.4-r2.ebuild, -xen-4.3.2.ebuild, +xen-4.3.2-r2.ebuild, + -xen-4.4.0.ebuild, -xen-4.4.0-r1.ebuild, +xen-4.4.0-r2.ebuild: + bump security patches, bug 508510, 508424, 509054, 509176 +*xen-tools-4.4.0-r2 (09 May 2014) +*xen-tools-4.3.2-r2 (09 May 2014) +*xen-tools-4.2.4-r2 (09 May 2014) + + 09 May 2014; Yixun Lan <dlan@gentoo.org> +xen-tools-4.2.4-r2.ebuild, + +xen-tools-4.3.2-r2.ebuild, +xen-tools-4.4.0-r2.ebuild, + +files/xen-tools-4-qemu-fix-po-collision.patch: + 1) bump security patches, bug 508510, 508424, 509054, 509176 2) fix file + collision with app-emulation/qemu, bug 508302 3) drop old
Arches, please test and mark stable: =app-emulation/xen-4.2.4-r2 =app-emulation/xen-tools-4.2.4-r2 =app-emulation/xen-pvgrub-4.2.4 Target keywords Both : "amd64 x86" =app-emulation/xen-4.3.2-r2 =app-emulation/xen-tools-4.3.2-r2 =app-emulation/xen-pvgrub-4.3.2 Target keywords Only: "amd64" after stabilization, we'll start to clean old ebuilds, thanks.
amd64 stable
x86 stable. Maintainer(s), please cleanup. Security, please vote.
tree cleaning was done, old versions were dropped, files in ${FILESDIR} were cleanup. And all security bugs should be addressed.
Maintainer(s), Thank you for cleanup! Security please Vote!
sorry, but it seems to me that too many xen security bugs are still marked as IN_PROGRESS status.. what do we still need to do? the vote? can we just get them closed? many thanks
(In reply to Yixun Lan from comment #7) > sorry, but it seems to me that too many xen security bugs are still marked > as IN_PROGRESS status.. what do we still need to do? the vote? can we just > get them closed? > > many thanks We need to follow the policy outlines in http://www.gentoo.org/security/en/vulnerability-policy.xml. Once we release the GLSA we will close the bugs.
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).
CVE-2014-3124 (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2014-3124): The HVMOP_set_mem_type control in Xen 4.1 through 4.4.x allows local guest HVM administrators to cause a denial of service (hypervisor crash) or possibly execute arbitrary code by leveraging a separate qemu-dm vulnerability to trigger invalid page table translations for unspecified memory page types.
