CVE-2021-47389: linux kernel — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: fix missing sev_decommission in sev_receive_start DECOMMISSION the current SEV context if binding an ASID fails after RECEIVE_START. Per AMD's SEV API, RECEIVE_START generates a new guest context and thus needs to be paired with DECOMMISSION: The RECEIVE_START command is the only command other than the LAUNCH_START command that generates a new guest context and guest handle. The missing DECOMMISSION can result in subsequent SEV launch failures, as the firmware leaks memory and might not able to allocate more SEV guest contexts in the future. Note, LAUNCH_START suffered the same bug, but was previously fixed by commit 934002cd660b ("KVM: SVM: Call SEV Guest Decommission if ASID binding fails").

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CVSS v3.1 Score

5.1

MEDIUM

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

Weakness Type (CWE)

CWE-772 CWE-772

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.13 — 5.14.10
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/efd7866e114dcb44f86d151e843f8276b7efbc67 https://git.kernel.org/stable/c/f1815e0aa770f2127c5df31eb5c2f0e37b60fa77 https://git.kernel.org/stable/c/efd7866e114dcb44f86d151e843f8276b7efbc67 https://git.kernel.org/stable/c/f1815e0aa770f2127c5df31eb5c2f0e37b60fa77

Frequently Asked Questions

What is CVE-2021-47389? +

In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: fix missing sev_decommission in sev_receive_start DECOMMISSION the current SEV context if binding an ASID fails after RECEIVE_START. Per AMD's SEV API, RECEIVE_START generates a new guest context and thus needs to be paired with DECOMMISSION: The RECEIVE_START command is the only command other than the LAUNCH_START command that generates a new guest context and guest handle. The missing DECOMMISSION can result in subsequent SEV launch failures, as the firmware leaks memory and might not able to allocate more SEV guest contexts in the future. Note, LAUNCH_START suffered the same bug, but was previously fixed by commit 934002cd660b ("KVM: SVM: Call SEV Guest Decommission if ASID binding fails"). It has a CVSS v3.1 base score of 5.1 (MEDIUM).

How severe is CVE-2021-47389? +

CVE-2021-47389 has a CVSS v3.1 score of 5.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2021-47389? +

CVE-2021-47389 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-2021-47389? +

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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