Date: Wed, 5 Sep 2012 10:38:44 +0100 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 12 (CVE-2012-3494) - hypercall set_debugreg vulnerability -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xen Security Advisory CVE-2012-3494 / XSA-12 version 3 hypercall set_debugreg vulnerability UPDATES IN VERSION 3 ==================== Public release. ISSUE DESCRIPTION ================= set_debugreg allows writes to reserved bits of the DR7 debug control register on x86-64. IMPACT ====== A malicious guest can cause the host to crash, leading to a DoS. If the vulnerable hypervisor is run on future hardware, the impact of the vulnerability might be widened depending on the future assignment of the currently-reserved debug register bits. VULNERABLE SYSTEMS ================== All systems running 64-bit paravirtualised guests. The vulnerability dates back to at least Xen 4.0. 4.0, 4.1, the 4.2 RCs, and xen-unstable.hg are all vulnerable. MITIGATION ========== This issue can be mitigated by ensuring (inside the guest) that the kernel is trustworthy, or by running only 32-bit or HVM guests. RESOLUTION ========== Applying the appropriate attached patch will resolve the issue. PATCH INFORMATION ================= The attached patch resolves this issue: Xen unstable, 4.1 and 4.0 xsa12-all.patch $ sha256sum xsa12-all.patch 2415ee133e28b1c848c5ae3ce766cc2a67009bad8d026879030a6511b85dbc13 xsa12-all.patch -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iQEcBAEBAgAGBQJQRx0+AAoJEIP+FMlX6CvZnMAH/0fcm9nfiChokydCyqXgdKtJ U2NqeqKzEP6emwLE+cvc+2EBP40fiBXsNATVdXc6Vx15eyzSMfJD3ndYF9OaKMVH MVP6KU/tyK1G/9WgQK9PHBj/Kzp8hwrY0Qw45od7z+R7XMGieLH9l1O1xwkNCYDw R8Xy2GI9IqsXLNpwy3BFYSyGYIX9o8/aBx4ZxHCV8H0OYUWv5hDGZZVXPDqGm11c N+qmUaPV2QlW8Aoww1SiwW5E+/CpyJT5+awEMgZ4IOHPbCBXJfyXbw4aMM2q5Soe mStqvPKL4H10SahaygdjxO+e4NqCHao0rYUXXpUr+aikIXvEearukp3FezR5IUE= =/LmZ -----END PGP SIGNATURE----- Download attachment "xsa12-all.patch" of type "application/octet-stream" (1011 bytes)
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