CVE Catalog

CVE-2022-49562

HighCVSS 7.8
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.27%

19th percentile - higher than 19% of all known CVEs

Summary

In the Linux kernel, KVM for x86 has a vulnerability in updating guest PTE A/D bits. The use of mapping the PTE into kernel address space is broken for VM_PFNMAP, potentially leading to access to random page frames.

Risk Assessment

Incorrect updating of A/D bits may lead to improper guest virtual memory behavior, potentially causing crashes or isolation breaches.

Recommendation

Apply a Linux kernel update containing the fix that uses __try_cmpxchg_user() to update A/D bits instead of mapping the PTE.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Use __try_cmpxchg_user() to update guest PTE A/D bits Use the recently introduced __try_cmpxchg_user() to update guest PTE A/D bits instead of mapping the PTE into kernel address space. The VM_PFNMAP path is broken as it assumes that vm_pgoff is the base pfn of the mapped VMA range, which is conceptually wrong as vm_pgoff is the offset relative to the file and has nothing to do with the pfn. The horrific hack worked for the original use case (backing guest memory with /dev/mem), but leads to accessing "random" pfns for pretty much any other VM_PFNMAP case.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS