The hypercall_create_continuation function in arch/arm/domain.c in Xen 4.4.x through 4.6.x allows local guest users to cause a denial of service (host crash) via a preemptible hypercall to the multicall interface.
The MITRE CVE dictionary describes this issue as:
Find out more about CVE-2015-7812 from the MITRE CVE dictionary dictionary and NIST NVD.
NOTE: The following CVSS v2 metrics and score provided are preliminary and subject to review.
| Base Score | 7.1 |
|---|---|
| Base Metrics | AV:N/AC:M/Au:N/C:N/I:N/A:C |
| Access Vector | Network |
| Access Complexity | Medium |
| Authentication | None |
| Confidentiality Impact | None |
| Integrity Impact | None |
| Availability Impact | Complete |
Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).
| Platform | Package | State |
|---|---|---|
| Red Hat Enterprise Linux 5 | xen | Not affected |
On systems where the guest kernel is controlled by the host rather than guest administrator, running only kernels which do not make use of multicall functionality will 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.
Vulmon