Date: Tue, 06 Jan 2015 12:40:41 +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@....org> Subject: Xen Security Advisory 116 (CVE-2015-0361) - xen crash due to use after free on hvm guest teardown -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xen Security Advisory CVE-2015-0361 / XSA-116 version 3 xen crash due to use after free on hvm guest teardown UPDATES IN VERSION 3 ==================== Public release. ISSUE DESCRIPTION ================= Certain data accessible (via hypercalls) by the domain controlling the execution of a HVM domain is being freed prematurely, leading to the respective memory regions to possibly be read from and written to in ways unexpected by their new owner(s). IMPACT ====== Malicious or buggy stub domain kernels or tool stacks otherwise living outside of Domain0 can mount a denial of service attack which, if successful, can affect the whole system. Only domains controlling HVM guests can exploit this vulnerability. (This includes domains providing hardware emulation services to HVM guests.) VULNERABLE SYSTEMS ================== Xen versions from 4.2 onwards are vulnerable on x86 systems. ARM systems are not vulnerable. This vulnerability is only applicable to Xen systems using stub domains or other forms of disaggregation of control domains for HVM guests. MITIGATION ========== Running only PV guests will avoid this issue. (The security of a Xen system using stub domains 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.) CREDITS ======= The issue was discovered by Mihai Donțu from Bitdefender who also supplied the fix. RESOLUTION ========== Applying the appropriate attached patch resolves this issue. xsa116.patch xen-unstable, Xen 4.4.x xsa116-4.3-4.2.patch Xen 4.3.x, Xen 4.2.x $ sha256sum xsa116*.patch 84b5a7bb2386e3d95d9d836a4a2504870723694ddaf537f1b59db75b7c63e9bd xsa116.patch 3aed6d157f62343a806347ea7c37bb8cdf50ee68002449bded9c7c1712810201 xsa116-4.3-4.2.patch $ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQEcBAEBAgAGBQJUq9eeAAoJEIP+FMlX6CvZZx8H/0jivCICcJ7SLhIJsAZAVwA4 gLpVaWk9qFMSUeYaccLG3naEHk/S5X8154J+VTb7cXDRFWI7lFAodUOhd0MRKzKc ZrauMNZDuUnjyJxQZEjreGQW/pfUO6IIsR/MOAPRoiyKOmOmSDoRTo7UJucZUgfr HtA5A58Fwiaw5t7LVXzxMI3EAR+ZL4M/e8Vv/F9sKfMSsGSfxPuTHVVoA1k9iUOF 6yq8pEX+BAZfZSVd2GokD0DipZwvULSlJNMlTBBhK7RGiUgzn6HaxLHvGxEg7JhC 0n97mVCJ8WIAwoqpEBU0E9xhN5Xxv4gTH5Dqhruw94X8gMhLe/BueYMXfYWIC18= =Z+TF -----END PGP SIGNATURE----- Download attachment "xsa116.patch" of type "application/octet-stream" (1012 bytes) Download attachment "xsa116-4.3-4.2.patch" of type "application/octet-stream" (913 bytes)
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