CVE-2020-11739
Published: 14 April 2020
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.
CVSS 3 base score: 7.8
Status
Package | Release | Status |
---|---|---|
xen Launchpad, Ubuntu, Debian |
Upstream |
Needs triage
|
Ubuntu 20.10 (Groovy Gorilla) |
Needs triage
|
|
Ubuntu 20.04 LTS (Focal Fossa) |
Needs triage
|
|
Ubuntu 18.04 LTS (Bionic Beaver) |
Needs triage
|
|
Ubuntu 16.04 LTS (Xenial Xerus) |
Needs triage
|
|
Ubuntu 14.04 ESM (Trusty Tahr) |
Does not exist
|
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Binaries built from this source package are in Universe and so are supported by the community. |
Notes
Author | Note |
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mdeslaur | hypervisor packages are in universe. For issues in the hypervisor, add appropriate tags to each section, ex: Tags_xen: universe-binary |