Date: Tue, 10 Dec 2013 12:58:33 +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 80 (CVE-2013-6400) - IOMMU TLB flushing may be inadvertently suppressed -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Xen Security Advisory CVE-2013-6400 / XSA-80 version 3 IOMMU TLB flushing may be inadvertently suppressed UPDATES IN VERSION 3 ==================== Public release. Corrected explanatory text to refer to the correct patch filename. ISSUE DESCRIPTION ================= An internal flag is used to temporarily suppress IOMMU TLB flushes, in order to consolidate multiple single page flushes into one wider flush. This flag is not cleared again, on certain error paths. This can result in TLB flushes not happening when they are needed. Retaining stale TLB entries could allow guests access to memory that ought to have been revoked, or grant greater access than intended. IMPACT ====== Malicious guest administrators might be able to cause host-wide denial of service, or escalate their privilege to that of the host. VULNERABLE SYSTEMS ================== Only VMs which have been assigned PCI devices can exploit the bug. Only systems using Intel VT-d are vulnerable, since the bug is in the VT-d specific code in Xen. Xen 4.2.x and later are vulnerable. Xen 4.1.x and earlier are not vulnerable. MITIGATION ========== This issue can be avoided by not assigning PCI devices to untrusted guests on systems supporting Intel VT-d. CREDITS ======= This issue was discovered by Jan Beulich. RESOLUTION ========== Applying the attached patch resolves this issue. xsa80.patch Xen 4.2.x, Xen 4.3.x, xen-unstable $ sha256sum xsa80*.patch d15e627c59dd48e1cacb2fbcd5e2148975daa426df1f693b991d69201c048e77 xsa80.patch $ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQEcBAEBAgAGBQJSpw/SAAoJEIP+FMlX6CvZu48IAIsJz4NRVXqCYl9hjtFhgfhL /V2J9T9Xp0/iNTmfP6FMu2wIZohAcosMOaZ5NXouIb50bta2mpeQhA0K0RZLEin5 2QH9rcfYYchAeQjPt72QVPH3iMTWdPXXV3HDuqXI+G+II64bonHvArtAwYxeJpWM ZwegEnxsEk2YsYk+TYGMzQws2sXygx06JxEJsE9/Q6BOJG9jnwvtRsleVDuMuBMR 6U1DdaxZohk5k1xqS5Y6udyXpJQgob7fMdwAoLWxxlb7vB3kOgzMoorVrzRZ0LcZ LmqBYxdCQRV+Tn19eE9xo1LjBr9qBS13nGDQbyIADoF85N/SmZoMycRsqunUQ2U= =rB23 -----END PGP SIGNATURE----- Download attachment "xsa80.patch" of type "application/octet-stream" (2072 bytes)
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