CVE-2021-47110: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: x86/kvm: Disable kvmclock on all CPUs on shutdown Currenly, we disable kvmclock from machine_shutdown() hook and this only happens for boot CPU. We need to disable it for all CPUs to guard against memory corruption e.g. on restore from hibernate. Note, writing '0' to kvmclock MSR doesn't clear memory location, it just prevents hypervisor from updating the location so for the short while after write and while CPU is still alive, the clock remains usable and correct so we don't need to switch to some other clocksource.

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CVSS v3.1 Score

7.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Weakness Type (CWE)

CWE-459 CWE-459

Affected Products

Vendor	Product	Versions
linux	linux_kernel	< 5.4.125
linux	linux_kernel	5.5 — 5.10.43
linux	linux_kernel	5.11 — 5.12.10
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/1df2dc09926f61319116c80ee85701df33577d70 https://git.kernel.org/stable/c/3b0becf8b1ecf642a9edaf4c9628ffc641e490d6 https://git.kernel.org/stable/c/9084fe1b3572664ad276f427dce575f580c9799a https://git.kernel.org/stable/c/c02027b5742b5aa804ef08a4a9db433295533046 https://git.kernel.org/stable/c/1df2dc09926f61319116c80ee85701df33577d70 https://git.kernel.org/stable/c/3b0becf8b1ecf642a9edaf4c9628ffc641e490d6 https://git.kernel.org/stable/c/9084fe1b3572664ad276f427dce575f580c9799a https://git.kernel.org/stable/c/c02027b5742b5aa804ef08a4a9db433295533046

Frequently Asked Questions

What is CVE-2021-47110? +

In the Linux kernel, the following vulnerability has been resolved: x86/kvm: Disable kvmclock on all CPUs on shutdown Currenly, we disable kvmclock from machine_shutdown() hook and this only happens for boot CPU. We need to disable it for all CPUs to guard against memory corruption e.g. on restore from hibernate. Note, writing '0' to kvmclock MSR doesn't clear memory location, it just prevents hypervisor from updating the location so for the short while after write and while CPU is still alive, the clock remains usable and correct so we don't need to switch to some other clocksource. It has a CVSS v3.1 base score of 7.1 (HIGH).

How severe is CVE-2021-47110? +

CVE-2021-47110 has a CVSS v3.1 score of 7.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2021-47110? +

CVE-2021-47110 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2021-47110? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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