Information Exposure Affecting kernel-64k-modules-extra package, versions *


Severity

Recommended
0.0
medium
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (11th percentile)

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  • Snyk IDSNYK-RHEL9-KERNEL64KMODULESEXTRA-8354124
  • published8 Nov 2024
  • disclosed5 Nov 2024

Introduced: 5 Nov 2024

CVE-2024-50102  (opens in a new tab)
CWE-203  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:9 kernel-64k-modules-extra.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-64k-modules-extra package and not the kernel-64k-modules-extra package as distributed by RHEL. See How to fix? for RHEL:9 relevant fixed versions and status.

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.

CVSS Scores

version 3.1