From ${URL} : A vulnerability has been reported in Xen, which can be exploited by malicious, local users in a guest virtual machine to cause a DoS (Denial of Service). The vulnerability is caused due to an error within the "vmx_set_uc_mode()" function, which can lead to subsequent requests to disable caches taking excessive time and cause a kernel panic. Successful exploitation requires HVM guests with PCI passthrough using the Intel variant of Hardware Assisted Paging (aka EPT). The vulnerability is reported versions 3.3 and later. Solution: No official solution is currently available. Provided and/or discovered by: The vendor credits Zhenzhong Duan. Original Advisory: XSA-60: http://www.openwall.com/lists/oss-security/2013/07/24/4 http://www.openwall.com/lists/oss-security/2013/07/24/5 http://www.openwall.com/lists/oss-security/2013/07/24/6 @maintainer(s): after the bump, in case we need to stabilize the package, please say explicitly if it is ready for the stabilization or not.
Solution Status: Unpatched Software: Xen 3.x Xen 4.x CVE Reference(s): CVE-2013-2212 Perhaps tell when they have one
CVE-2013-2212 (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2013-2212): The vmx_set_uc_mode function in Xen 3.3 through 4.3, when disabling chaches, allows local HVM guests with access to memory mapped I/O regions to cause a denial of service (CPU consumption and possibly hypervisor or guest kernel panic) via a crafted GFN range.
http://xenbits.xen.org/xsa/advisory-60.html still reads RESOLUTION ========== There is currently no resolution to this issue.
from http://www.openwall.com/lists/oss-security/2014/02/19/5 : Xen Security Advisory CVE-2013-2212 / XSA-60 version 6 Excessive time to disable caching with HVM guests with PCI passthrough UPDATES IN VERSION 6 ==================== Since the issue of this advisory, various fixes have been applied to the public Xen trees. ISSUE DESCRIPTION ================= HVM guests are able to manipulate their physical address space such that processing a subsequent request by that guest to disable caches takes an extended amount of time changing the cachability of the memory pages assigned to this guest. This applies only when the guest has been granted access to some memory mapped I/O region (typically by way of assigning a passthrough PCI device). This can cause the CPU which processes the request to become unavailable, possibly causing the hypervisor or a guest kernel (including the domain 0 one) to halt itself ("panic"). IMPACT ====== A malicious domain, given access to a device with memory mapped I/O regions, can cause the host to become unresponsive for a period of time, potentially leading to a DoS affecting the whole system. VULNERABLE SYSTEMS ================== Xen version 3.3 onwards is vulnerable. Only systems using the Intel variant of Hardware Assisted Paging (aka EPT) are vulnerable. MITIGATION ========== This issue can be avoided by not assigning PCI devices to untrusted guests, or by running HVM guests with shadow mode paging (through adding "hap=0" to the domain configuration file). CREDITS ======= Zhenzhong Duan found the issue as a bug, which on examination by the Xenproject.org Security Team turned out to be a security problem. RESOLUTION ========== This issue has been fixed in the public xen.git trees. For xen-unstable (#staging, #master), in these git commits: c13b0d65ddedd745 VMX: disable EPT when !cpu_has_vmx_pat 1c84d046735102e0 VMX: remove the problematic set_uc_mode logic 62652c00efa55fb4 VMX: fix cr0.cd handling 86d60e855fe118df VMX: flush cache when vmentry back to UC guest f1c9658d6802c433 Revert "VMX: flush cache when vmentry back to UC guest" (Earliest commit is listed first. Note that f1c9658d reverts not only 86d60e85 but also part of 62652c00.) For Xen 4.2 (#staging-4.2, #stable-4.2): f1e0df14412c VMX: disable EPT when !cpu_has_vmx_pat 644e6c5c7106 VMX: remove the problematic set_uc_mode logic 0fffcffeb594 VMX: fix cr0.cd handling
> For xen-unstable (#staging, #master), in these git commits: > c13b0d65ddedd745 VMX: disable EPT when !cpu_has_vmx_pat > 1c84d046735102e0 VMX: remove the problematic set_uc_mode logic > 62652c00efa55fb4 VMX: fix cr0.cd handling > 86d60e855fe118df VMX: flush cache when vmentry back to UC guest > f1c9658d6802c433 Revert "VMX: flush cache when vmentry back to UC guest" > (Earliest commit is listed first. Note that f1c9658d reverts > not only 86d60e85 but also part of 62652c00.) > we didn't package for #staging, #master, so it not affacted > For Xen 4.2 (#staging-4.2, #stable-4.2): > f1e0df14412c VMX: disable EPT when !cpu_has_vmx_pat > 644e6c5c7106 VMX: remove the problematic set_uc_mode logic > 0fffcffeb594 VMX: fix cr0.cd handling for >=xen-4.2.3.ebuild, XSA-60 is already fixed , thanks
Maintainer(s), Thank you for you for cleanup. Added to an existing GLSA Request.
This issue was resolved and addressed in GLSA 201504-04 at https://security.gentoo.org/glsa/201504-04 by GLSA coordinator Yury German (BlueKnight).
