|Summary:||CVE-2015-7813 xen: Various unimplemented hypercalls log without rate limiting on ARM|
|Product:||[Other] Security Response||Reporter:||Adam Mariš <amaris>|
|Component:||vulnerability||Assignee:||Red Hat Product Security <security-response-team>|
|Status:||CLOSED NOTABUG||QA Contact:|
|Version:||unspecified||CC:||ailan, drjones, imammedo, knoel, mrezanin, pbonzini, rkrcmar, security-response-team, vkuznets, xen-maint|
|Fixed In Version:||Doc Type:||Bug Fix|
|Doc Text:||Story Points:||---|
|Last Closed:||2018-03-07 09:49:56 UTC||Type:||---|
|oVirt Team:||---||RHEL 7.3 requirements from Atomic Host:|
|Cloudforms Team:||---||Target Upstream Version:|
|Bug Depends On:||1276344|
Description Adam Mariš 2015-10-14 12:07:55 UTC
A vulnerability allowing malicious guest to cause Denial of Service. The HYPERVISOR_physdev_op hypercall and most suboperations of the HYPERVISOR_hvm_op hypercall are not currently implemented by Xen on ARM and when called will log the use to the hypervisor console. However these guest accessible log messages are not rate-limited. A malicious guest could cause repeated logging to the hypervisor console, leading to a Denial of Service attack. Xen 4.4 and later systems running on ARM hardware are vulnerable. Mitigation: The problematic log messages are issued with priority Warning. Therefore they can be rate limited by adding "loglvl=error/warning" to the hypervisor command line or suppressed entirely by adding "loglvl=error". On systems where the guest kernel is controlled by the host rather than guest administrator, running only kernels which do not call these hypercalls will also prevent untrusted guest users from exploiting this issue. However untrusted guest administrators can still trigger it unless further steps are taken to prevent them from loading code into the kernel (e.g. by disabling loadable modules etc) or from using other mechanisms which allow them to run code at kernel privilege.
Comment 2 Martin Prpič 2015-10-29 13:38:28 UTC
External References: http://xenbits.xen.org/xsa/advisory-146.html
Comment 3 Martin Prpič 2015-10-29 13:51:14 UTC
Created xen tracking bugs for this issue: Affects: fedora-all [bug 1276344]
Comment 4 Fedora Update System 2015-11-08 22:20:49 UTC
xen-4.5.1-14.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.
Comment 5 Fedora Update System 2015-11-10 00:22:03 UTC
xen-4.5.1-14.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.
Comment 6 Fedora Update System 2015-11-10 00:50:11 UTC
xen-4.4.3-7.fc21 has been pushed to the Fedora 21 stable repository. If problems still persist, please make note of it in this bug report.