Red Hat Security Advisory: kernel security update Security Advisory secalert@redhat.com Red Hat Security Response Team RHSA-2012:0721 Final 1 1 2012-06-12T12:29:00Z Current version 2012-06-12T12:29:00Z 2012-06-12T12:29:00Z Red Hat rhsa-to-cvrf 1.0.1484 2012-06-12T14:56:16Z Updated kernel packages that fix two security issues are now available for Red Hat Enterprise Linux 5. The Red Hat Security Response Team has rated this update as having important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section. The kernel packages contain the Linux kernel, the core of any Linux operating system. This update fixes the following security issues: * It was found that the Xen hypervisor implementation as shipped with Red Hat Enterprise Linux 5 did not properly restrict the syscall return addresses in the sysret return path to canonical addresses. An unprivileged user in a 64-bit para-virtualized guest, that is running on a 64-bit host that has an Intel CPU, could use this flaw to crash the host or, potentially, escalate their privileges, allowing them to execute arbitrary code at the hypervisor level. (CVE-2012-0217, Important) * It was found that guests could trigger a bug in earlier AMD CPUs, leading to a CPU hard lockup, when running on the Xen hypervisor implementation. An unprivileged user in a 64-bit para-virtualized guest could use this flaw to crash the host. Warning: After installing this update, hosts that are using an affected AMD CPU (refer to Red Hat Bugzilla bug #824966 for a list) will fail to boot. In order to boot such hosts, the new kernel parameter, allow_unsafe, can be used ("allow_unsafe=on"). This option should only be used with hosts that are running trusted guests, as setting it to "on" reintroduces the flaw (allowing guests to crash the host). (CVE-2012-2934, Moderate) Note: For Red Hat Enterprise Linux guests, only privileged guest users can exploit the CVE-2012-0217 and CVE-2012-2934 issues. Red Hat would like to thank the Xen project for reporting these issues. Upstream acknowledges Rafal Wojtczuk as the original reporter of CVE-2012-0217. Users should upgrade to these updated packages, which contain backported patches to correct these issues. The system must be rebooted for this update to take effect. Please see https://www.redhat.com/footer/terms-of-use.html Copyright © 2012 Red Hat, Inc. All rights reserved. Important https://rhn.redhat.com/errata/RHSA-2012-0721.html https://rhn.redhat.com/errata/RHSA-2012-0721.html https://access.redhat.com/security/updates/classification/#important https://access.redhat.com/security/updates/classification/#important https://bugzilla.redhat.com/show_bug.cgi?id=824966 https://bugzilla.redhat.com/show_bug.cgi?id=824966 Red Hat Enterprise Linux Desktop (v. 5 client) Red Hat Enterprise Linux (v. 5 server) kernel-2.6.18-308.8.2.el5.src.rpm kernel-2.6.18-308.8.2.el5 as a component of Red Hat Enterprise Linux Desktop (v. 5 client) kernel-2.6.18-308.8.2.el5 as a component of Red Hat Enterprise Linux (v. 5 server) It was found that the Xen hypervisor implementation as shipped with Red Hat Enterprise Linux 5 did not properly restrict the syscall return addresses in the sysret return path to canonical addresses. An unprivileged user in a 64-bit para-virtualized guest, that is running on a 64-bit host that has an Intel CPU, could use this flaw to crash the host or, potentially, escalate their privileges, allowing them to execute arbitrary code at the hypervisor level. Note: For Red Hat Enterprise Linux guests, only privileged guest users can exploit the CVE-2012-0217 and CVE-2012-2934 issues. 2012-04-17T00:00:00Z 2012-06-12T00:00:00Z CVE-2012-0217 5Client-5.8.Z:kernel-2.6.18-308.8.2.el5 5Server-5.8.Z:kernel-2.6.18-308.8.2.el5 Important 7.9 AV:A/AC:M/Au:N/C:C/I:C/A:C Before applying this update, make sure all previously-released errata relevant to your system have been applied. This update is available via the Red Hat Network. Details on how to use the Red Hat Network to apply this update are available at https://access.redhat.com/knowledge/articles/11258 To install kernel packages manually, use "rpm -ivh [package]". Do not use "rpm -Uvh" as that will remove the running kernel binaries from your system. You may use "rpm -e" to remove old kernels after determining that the new kernel functions properly on your system. https://rhn.redhat.com/errata/RHSA-2012-0721.html https://www.redhat.com/security/data/cve/CVE-2012-0217.html CVE-2012-0217 https://bugzilla.redhat.com/show_bug.cgi?id=813428 bz#813428: CVE-2012-0217 kernel: x86-64: avoid sysret to non-canonical address Red Hat would like to thank the Xen project for reporting this issue. Upstream acknowledges Rafal Wojtczuk as the original reporter. It was found that guests could trigger a bug in earlier AMD CPUs, leading to a CPU hard lockup, when running on the Xen hypervisor implementation. An unprivileged user in a 64-bit para-virtualized guest could use this flaw to crash the host. Warning: After installing this update, hosts that are using an affected AMD CPU (refer to Red Hat Bugzilla bug #824966 for a list) will fail to boot. In order to boot such hosts, the new kernel parameter, allow_unsafe, can be used ("allow_unsafe=on"). This option should only be used with hosts that are running trusted guests, as setting it to "on" reintroduces the flaw (allowing guests to crash the host). Note: For Red Hat Enterprise Linux guests, only privileged guest users can exploit the CVE-2012-0217 and CVE-2012-2934 issues. 2012-05-24T00:00:00Z 2012-06-12T00:00:00Z CVE-2012-2934 5Client-5.8.Z:kernel-2.6.18-308.8.2.el5 5Server-5.8.Z:kernel-2.6.18-308.8.2.el5 Moderate 4.6 AV:A/AC:H/Au:N/C:N/I:N/A:C Before applying this update, make sure all previously-released errata relevant to your system have been applied. This update is available via the Red Hat Network. Details on how to use the Red Hat Network to apply this update are available at https://access.redhat.com/knowledge/articles/11258 To install kernel packages manually, use "rpm -ivh [package]". Do not use "rpm -Uvh" as that will remove the running kernel binaries from your system. You may use "rpm -e" to remove old kernels after determining that the new kernel functions properly on your system. https://rhn.redhat.com/errata/RHSA-2012-0721.html https://www.redhat.com/security/data/cve/CVE-2012-2934.html CVE-2012-2934 https://bugzilla.redhat.com/show_bug.cgi?id=824966 bz#824966: CVE-2012-2934 kernel: denial of service due to AMD Erratum #121 Red Hat would like to thank the Xen project for reporting this issue.