Out-of-Bounds Affecting xen package, versions <4.13.0-r3


0.0
high

Snyk CVSS

    Attack Complexity High
    Scope Changed
    Confidentiality High
    Integrity High
    Availability High

    Threat Intelligence

    EPSS 0.05% (13th percentile)
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NVD
7.8 high
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SUSE
7.8 high

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  • Snyk ID SNYK-ALPINE314-XEN-1308480
  • published 21 Jul 2020
  • disclosed 14 Apr 2020

How to fix?

Upgrade Alpine:3.14 xen to version 4.13.0-r3 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream xen package and not the xen package as distributed by Alpine. See How to fix? for Alpine:3.14 relevant fixed versions and status.

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.