Linux Kernel up to 5.11.20/5.12/5.12.3 SVM kvm_for_each_vcpu null pointer dereference

Summaryinfo

A vulnerability has been found in Linux Kernel up to 5.11.20/5.12/5.12.3 and classified as critical. The affected element is the function kvm_for_each_vcpu of the component SVM. This manipulation causes null pointer dereference. The identification of this vulnerability is CVE-2021-47062. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 5.11.20/5.12/5.12.3 (Operating System). Affected by this vulnerability is the function kvm_for_each_vcpu of the component SVM. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Use online_vcpus, not created_vcpus, to iterate over vCPUs Use the kvm_for_each_vcpu() helper to iterate over vCPUs when encrypting VMSAs for SEV, which effectively switches to use online_vcpus instead of created_vcpus. This fixes a possible null-pointer dereference as created_vcpus does not guarantee a vCPU exists, since it is updated at the very beginning of KVM_CREATE_VCPU. created_vcpus exists to allow the bulk of vCPU creation to run in parallel, while still correctly restricting the max number of max vCPUs.

The weakness was shared 03/01/2024. The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2021-47062 since 02/29/2024. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 250137 (Linux Distros Unpatched Vulnerability : CVE-2021-47062), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.11.21, 5.12.4 or 5.13 eliminates this vulnerability. Applying the patch bd0cced2ae93/ba7bf5d6336a/c36b16d29f3a 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.

The vulnerability is also documented in the vulnerability database at Tenable (250137). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.0
• 5.1
• 5.2
• 5.3
• 5.4
• 5.5
• 5.6
• 5.7
• 5.8
• 5.9
• 5.10
• 5.11
• 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
• 5.12
• 5.12.0
• 5.12.1
• 5.12.2
• 5.12.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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