Date: Tue, 12 Sep 2017 12:03:34 +0000 From: Xen.org security team <security@....org> To: xen-announce@...ts.xen.org, xen-devel@...ts.xen.org, xen-users@...ts.xen.org, oss-security@...ts.openwall.com CC: Xen.org security team <security-team-members@....org> Subject: Xen Security Advisory 233 (CVE-2017-14317) - cxenstored: Race in domain cleanup -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Xen Security Advisory CVE-2017-14317 / XSA-233 version 3 cxenstored: Race in domain cleanup UPDATES IN VERSION 3 ==================== Added metadata file Public release. ISSUE DESCRIPTION ================= When shutting down a VM with a stubdomain, a race in cxenstored may cause a double-free. IMPACT ====== The xenstored daemon may crash, resulting in a DoS of any parts of the system relying on it (including domain creation / destruction, ballooning, device changes, etc). VULNERABLE SYSTEMS ================== All versions of Xen are vulnerable. Only systems running the C version os xenstored ("xenstored") are vulnerable; systems running the Ocaml version ("oxenstored") are not vulnerable. Only systems running devicemodel stubdomains are vulnerable. Only x86 HVM guests can use stubdomains. Therefore ARM systems, x86 systems running only PV guests, and x86 systems running HVM guests with the devicemodel not in a stubdomain (eg in dom0), are not vulnerable. MITIGATION ========== Running oxenstored will mitigate this issue. Not using stubdomains will also mitigate the issue. CREDITS ======= This issue was discovered by Eric Chanudet of AIS. RESOLUTION ========== Applying the attached patch resolves this issue. xsa233.patch xen-unstable, Xen 4.9.x Xen 4.8.x Xen 4.7.x Xen 4.6.x Xen 4.5.x $ sha256sum xsa233* 66b6f6c0837a5d12a77db7e5cbfd0514968bd47e2d192824da3bc9ddf119bfe0 xsa233.meta f721cc49ba692b2f36299b631451f51d7340b8b4732f74c98f01cb7a80d8662b xsa233.patch $ DEPLOYMENT DURING EMBARGO ========================= Deployment of the patches and/or mitigations described above (or others which are substantially similar) is permitted during the embargo, even on public-facing systems with untrusted guest users and administrators. But: Distribution of updated software is prohibited (except to other members of the predisclosure list). Predisclosure list members who wish to deploy significantly different patches and/or mitigations, please contact the Xen Project Security Team. (Note: this during-embargo deployment notice is retained in post-embargo publicly released Xen Project advisories, even though it is then no longer applicable. This is to enable the community to have oversight of the Xen Project Security Team's decisionmaking.) For more information about permissible uses of embargoed information, consult the Xen Project community's agreed Security Policy: http://www.xenproject.org/security-policy.html -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBCAAGBQJZt80GAAoJEIP+FMlX6CvZVO8IALTEAV/xiPTN1uUPISLQYLmX 6Bu80yrD+5UjVVI01FrkeUfNJBABmxf5q6sTOFeuYctwY6iPMJI46jHda8ugew5j wnOgtgat0lfQT1/E/C8SsGEHeTULXPHVOaaXRQT55ExhVvEhLvSQV5vd6YNituyq ow3hYrK3crK3uCOdLyZlxbuHXMFyLIbpoTYnRgXzV/3uLOB5TPsoRzKf4E+Z1Muo chQXk8OQG+CEYupf00+H/QTvrDLSnf4KT4t4rZXDqUd39QoxV1l9s0daLyMjyJg/ Lu5t1WmcmarZvYICJhWf3Vi2NpaNTyQEeepwUM/XHe+vgHJXzesWyuRoLApmEfE= =trYV -----END PGP SIGNATURE----- Download attachment "xsa233.meta" of type "application/octet-stream" (1829 bytes) Download attachment "xsa233.patch" of type "application/octet-stream" (1776 bytes)
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