CVE-2024-44965: x86/mm: Fix pti_clone_pgtable() alignment assumption

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-09-04 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: x86/mm: Fix pti_clone_pgtable() alignment assumption Guenter reported dodgy crashes on an i386-nosmp build using GCC-11 that had the form of endless traps until entry stack exhaust and then #DF from the stack guard. It turned out that pti_clone_pgtable() had alignment assumptions on the start address, notably it hard assumes start is PMD aligned. This is true on x86_64, but very much not true on i386. These assumptions can cause the end condition to malfunction, leading to a 'short' clone. Guess what happens when the user mapping has a short copy of the entry text? Use the correct increment form for addr to avoid alignment assumptions.

Affected products

Linux kernel: from 4.19 before 4.19.320; from 4.20 before 5.4.282; from 5.5 before 5.10.224; from 5.11 before 5.15.165; from 5.16 before 6.1.105; from 6.2 before 6.6.46 — fixed in 4.19.320, 5.10.224, 5.15.165, 5.4.282, 6.1.105, 6.10.5

How to fix

Upgrade to a fixed version: Linux kernel 4.19.320, 5.10.224, 5.15.165, 5.4.282. Check the vendor advisory for mitigations.

References

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