CVE Catalog

CVE-2024-50102

MediumCVSS 5.5
Published: Updated: Translated: NVD NIST

Summary

In the Linux kernel, a speculative execution issue exists with non-canonical address accesses on AMD Zen 5 CPUs. Due to AC bit renaming, the speculation window remains open, potentially leaking speculative data through a suitable gadget. This affects user address masking, valid_user_address() checks, and get_user() helpers.

Risk Assessment

Could allow an attacker to leak kernel memory data on AMD Zen 5 processors, posing a confidentiality risk. Exploitation requires a suitable gadget and local access.

Recommendation

Update the Linux kernel to a version containing the fix. Monitor systems with AMD Zen 5 CPUs for unusual activity.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: x86: fix user address masking non-canonical speculation issue It turns out that AMD has a "Meltdown Lite(tm)" issue with non-canonical accesses in kernel space. And so using just the high bit to decide whether an access is in user space or kernel space ends up with the good old "leak speculative data" if you have the right gadget using the result: CVE-2020-12965 “Transient Execution of Non-Canonical Accesses“ Now, the kernel surrounds the access with a STAC/CLAC pair, and those instructions end up serializing execution on older Zen architectures, which closes the speculation window. But that was true only up until Zen 5, which renames the AC bit [1]. That improves performance of STAC/CLAC a lot, but also means that the speculation window is now open. Note that this affects not just the new address masking, but also the regular valid_user_address() check used by access_ok(), and the asm version of the sign bit check in the get_user() helpers. It does not affect put_user() or clear_user() variants, since there's no speculative result to be used in a gadget for those operations.

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