CVE-2021-47008

KVM: SVM: Make sure GHCB is mapped before updating

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Make sure GHCB is mapped before updating Access to the GHCB is mainly in the VMGEXIT path and it is known that the GHCB will be mapped. But there are two paths where it is possible the GHCB might not be mapped. The sev_vcpu_deliver_sipi_vector() routine will update the GHCB to inform the caller of the AP Reset Hold NAE event that a SIPI has been delivered. However, if a SIPI is performed without a corresponding AP Reset Hold, then the GHCB might not be mapped (depending on the previous VMEXIT), which will result in a NULL pointer dereference. The svm_complete_emulated_msr() routine will update the GHCB to inform the caller of a RDMSR/WRMSR operation about any errors. While it is likely that the GHCB will be mapped in this situation, add a safe guard in this path to be certain a NULL pointer dereference is not encountered.

Category

5.5
CVSS
Severity: Medium
CVSS 3.1 •
EPSS 0.04%
Affected: Linux Linux
Affected: Linux Linux
Published at:
Updated at:

References

Link Tags
https://git.kernel.org/stable/c/fb9e14f4f8217a0980f8da2c8ff70dee058cbe47 patch
https://git.kernel.org/stable/c/fd722a57fe0b80133dacae4e1c852ee4212f9b2e patch
https://git.kernel.org/stable/c/a3ba26ecfb569f4aa3f867e80c02aa65f20aadad patch

Frequently Asked Questions

What is the severity of CVE-2021-47008?
CVE-2021-47008 has been scored as a medium severity vulnerability.
How to fix CVE-2021-47008?
To fix CVE-2021-47008, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-47008 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2021-47008 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-47008?
CVE-2021-47008 affects Linux Linux, Linux Linux.
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