PT-2021-8125 · Linux+1 · Linux Kernel+1

Published 2021-12-20 · Updated 2024-10-11 · CVE-2021-47092

Positive Technologies (AI Summary)

CVSS v3.1

5.5

Medium

Base vector

AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description The vulnerability is related to the KVM component of the Linux kernel. It is caused by the incorrect handling of the vmx->fail flag when the vCPU is in L2 and emulation required is true. This behavior is considered bogus and can lead to a WARN in nested vmx vmexit() when tearing down the VM. The issue arises because setting vmx->fail and synthesizing a VM-Exit is contradictory and wrong. Specifically, it is impossible to have both a VM-Fail and VM-Exit, vmcs.EXIT REASON is not modified on VM-Fail, and emulation required refers to guest state and guest state checks are always VM-Exits, not VM-Fails. For KVM, emulation required is handled before nested exits in vmx handle exit(), thus setting vmx->fail has no immediate effect.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Improper Resource Release

Weakness Enumeration

CWE-404

Related Identifiers

BDU:2024-08382

CVE-2021-47092

Affected Products

Linux Kernel

Red Os

References · 18

• https://ubuntu.com/security/CVE-2021-47092 · Vendor Advisory
• https://bdu.fstec.ru/vul/2024-08382 · Security Note
• https://git.kernel.org/stable/c/e4e4e7cb229821cd215031abc47efdab5486a67c · Patch
• https://git.kernel.org/stable/c/a80dfc025924024d2c61a4c1b8ef62b2fce76a04 · Patch
• https://osv.dev/vulnerability/CVE-2021-47092 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2021-47092 · Security Note
• https://security-tracker.debian.org/tracker/CVE-2021-47092 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2021-47092 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2021-47092 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2021-47092 · Vendor Advisory
• https://redos.red-soft.ru/support/secure/uyazvimosti/support/secure/uyazvimosti/mnozhestvennye-uyazvimosti-kernel-lt-11-10-24-1 · Note
• https://redos.red-soft.ru/support/secure · Note
• https://lore.kernel.org/linux-cve-announce/2024030414-CVE-2021-47092-36e2@gregkh · Note
• https://git.kernel.org/linus/a80dfc025924024d2c61a4c1b8ef62b2fce76a04 · Note
• https://kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.15.12 · Note