Linux Kernel up to 5.11.21/5.12.4 SVM sev_vcpu_deliver_sipi_vector null pointer dereference

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 5.11.21/5.12.4. Affected by this issue is the function sev_vcpu_deliver_sipi_vector of the component SVM. The manipulation leads to null pointer dereference. This vulnerability is uniquely identified as CVE-2021-47008. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 5.11.21/5.12.4 (Operating System) and classified as critical. This issue affects the function sev_vcpu_deliver_sipi_vector of the component SVM. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. The summary by CVE is:

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.

The weakness was disclosed 02/28/2024. It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2021-47008 since 02/27/2024. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 5.11.22, 5.12.5 or 5.13 eliminates this vulnerability. Applying the patch fb9e14f4f821/fd722a57fe0b/a3ba26ecfb56 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.11.0
• 5.11.1
• 5.11.2
• 5.11.3
• 5.11.4
• 5.11.5
• 5.11.6
• 5.11.7
• 5.11.8
• 5.11.9
• 5.11.10
• 5.11.11
• 5.11.12
• 5.11.13
• 5.11.14
• 5.11.15
• 5.11.16
• 5.11.17
• 5.11.18
• 5.11.19
• 5.11.20
• 5.11.21
• 5.12.0
• 5.12.1
• 5.12.2
• 5.12.3
• 5.12.4

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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