Date: Tue, 08 Jan 2019 16:44:12 +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 277 v3 (CVE-2018-19964) - x86: incorrect error handling for guest p2m page removals -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Xen Security Advisory CVE-2018-19964 / XSA-277 version 3 x86: incorrect error handling for guest p2m page removals UPDATES IN VERSION 3 ==================== CVE assigned. ISSUE DESCRIPTION ================= The internal function querying a domain's p2m table grabs the p2m lock by default, so that the answer to the query remains true until the caller can act on that information; it is up to the caller then to release the lock. Unfortunately, certain failure paths don't release the lock. IMPACT ====== A malicious or buggy guest may cause a deadlock, resulting in a DoS (Denial of Service) affecting the entire host. VULNERABLE SYSTEMS ================== Xen 4.11 and onward are vulnerable. Only x86 systems are vulnerable. ARM systems are not vulnerable. Only systems running untrusted HVM or PVH guests are vulnerable. Systems running only PV guests are not vulnerable. MITIGATION ========== Running only PV guests will avoid this vulnerability. CREDITS ======= This issue was discovered by Paul Durrant of Citrix. RESOLUTION ========== Applying the appropriate attached patch resolves this issue. xsa277.patch xen-unstable, Xen 4.11.x $ sha256sum xsa277* 576cdc05975e43698624b88f7290119dd702b3db8f30f3219754d992d7fef0c6 xsa277.meta c9025e1daaec4081a61f1ed7b96e69cfe8e35bdd5b4fcc0fadc98f71c2e243e2 xsa277.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deployment notice is retained in post-embargo publicly released Xen Project advisories, even though it is then no longer applicable.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----- iQFABAEBCAAqFiEEI+MiLBRfRHX6gGCng/4UyVfoK9kFAlw00y8MHHBncEB4ZW4u b3JnAAoJEIP+FMlX6CvZN+YH/2HCZYKrgxQzQIfNMO+2magHgzrlY0YCzmmgSpJD StrtQ//XSg4KbBsdRJbMZLPcAhXFRBPWueW+p/Tv2ANyPc95hLh1mrhS8DshbJ4v C2istb+FLiGKCuhqKbdxmvR7f73Htu7lcZ10J1EDbtwYufXnsDMfkzLLeHaKDCnV Cw0igX3yL2Puj3DhNZg7HrD77wKvkaX2eDNUGsivq/PhnhYD4wuP0Jo6QVO749nI ugDBhvavnV3JODFhfS+4g6M8NMwjLMedsmbCv5pGsd4hBj/lb4hgkMXanKy+bRUv Te2YiJZ4gwpkVKgpyG0uzIb9xg14uTYfemFE+fVNhO+zUQE= =Anj0 -----END PGP SIGNATURE----- Download attachment "xsa277.meta" of type "application/octet-stream" (666 bytes) Download attachment "xsa277.patch" of type "application/octet-stream" (1835 bytes)
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