Use After Free Affecting kernel package, versions <0:4.14.214-118.339.amzn1


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.05% (16th percentile)

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  • Snyk IDSNYK-AMZN201803-KERNEL-1726347
  • published27 Sept 2021
  • disclosed15 Dec 2020

Introduced: 15 Dec 2020

CVE-2020-29569  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2018.03 kernel to version 0:4.14.214-118.339.amzn1 or higher.
This issue was patched in ALAS-2021-1477.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel package and not the kernel package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2018.03 relevant fixed versions and status.

An issue was discovered in the Linux kernel through 5.10.1, as used with Xen through 4.14.x. The Linux kernel PV block backend expects the kernel thread handler to reset ring->xenblkd to NULL when stopped. However, the handler may not have time to run if the frontend quickly toggles between the states connect and disconnect. As a consequence, the block backend may re-use a pointer after it was freed. A misbehaving guest can trigger a dom0 crash by continuously connecting / disconnecting a block frontend. Privilege escalation and information leaks cannot be ruled out. This only affects systems with a Linux blkback.

CVSS Scores

version 3.1