An issue was discovered in Xen through 4.13.x, allowing guest OS users to cause a denial of service or possibly gain privileges because of missing memory barriers in read-write unlock paths. The read-write unlock paths don't contain a memory barrier. On Arm, this means a processor is allowed to re-order the memory access with the preceding ones. In other words, the unlock may be seen by another processor before all the memory accesses within the "critical" section. As a consequence, it may be possible to have a writer executing a critical section at the same time as readers or another writer. In other words, many of the assumptions (e.g., a variable cannot be modified after a check) in the critical sections are not safe anymore. The read-write locks are used in hypercalls (such as grant-table ones), so a malicious guest could exploit the race. For instance, there is a small window where Xen can leak memory if XENMAPSPACE_grant_table is used concurrently. A malicious guest may be able to leak memory, or cause a hypervisor crash resulting in a Denial of Service (DoS). Information leak and privilege escalation cannot be excluded.
History

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cve-icon MITRE Information

Status: PUBLISHED

Assigner: mitre

Published: 2020-04-14T12:17:49

Updated: 2020-07-13T15:06:02

Reserved: 2020-04-14T00:00:00


Link: CVE-2020-11739

JSON object: View

cve-icon NVD Information

Status : Modified

Published: 2020-04-14T13:15:12.703

Modified: 2023-11-07T03:15:04.020


Link: CVE-2020-11739

JSON object: View

cve-icon Redhat Information

No data.

CWE