Linux Kernel up to 5.15.21/5.16.7 arm64 fixup_guest_exit privilege escalation

Summaryinfo

A vulnerability categorized as problematic has been discovered in Linux Kernel up to 5.15.21/5.16.7. Affected by this vulnerability is the function fixup_guest_exit of the component arm64. The manipulation results in an unknown weakness. This vulnerability is cataloged as CVE-2022-48727. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 5.15.21/5.16.7. It has been classified as problematic. Affected is the function fixup_guest_exit of the component arm64. The impact remains unknown. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Avoid consuming a stale esr value when SError occur When any exception other than an IRQ occurs, the CPU updates the ESR_EL2 register with the exception syndrome. An SError may also become pending, and will be synchronised by KVM. KVM notes the exception type, and whether an SError was synchronised in exit_code. When an exception other than an IRQ occurs, fixup_guest_exit() updates vcpu->arch.fault.esr_el2 from the hardware register. When an SError was synchronised, the vcpu esr value is used to determine if the exception was due to an HVC. If so, ELR_EL2 is moved back one instruction. This is so that KVM can process the SError first, and re-execute the HVC if the guest survives the SError. But if an IRQ synchronises an SError, the vcpu's esr value is stale. If the previous non-IRQ exception was an HVC, KVM will corrupt ELR_EL2, causing an unrelated guest instruction to be executed twice. Check ARM_EXCEPTION_CODE() before messing with ELR_EL2, IRQs don't update this register so don't need to check.

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2022-48727. Technical details are known, but there is no available exploit.

Upgrading to version 5.15.22 or 5.16.8 eliminates this vulnerability. Applying the patch e1e852746997/57e2986c3b25/1c71dbc8a179 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

• 5.15.0
• 5.15.1
• 5.15.2
• 5.15.3
• 5.15.4
• 5.15.5
• 5.15.6
• 5.15.7
• 5.15.8
• 5.15.9
• 5.15.10
• 5.15.11
• 5.15.12
• 5.15.13
• 5.15.14
• 5.15.15
• 5.15.16
• 5.15.17
• 5.15.18
• 5.15.19
• 5.15.20
• 5.15.21
• 5.16.0
• 5.16.1
• 5.16.2
• 5.16.3
• 5.16.4
• 5.16.5
• 5.16.6
• 5.16.7

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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