CVE-2024-50199: mm/swapfile: skip HugeTLB pages for unuse_vma

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: 2024-11-08 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: mm/swapfile: skip HugeTLB pages for unuse_vma I got a bad pud error and lost a 1GB HugeTLB when calling swapoff. The problem can be reproduced by the following steps: 1. Allocate an anonymous 1GB HugeTLB and some other anonymous memory. 2. Swapout the above anonymous memory. 3. run swapoff and we will get a bad pud error in kernel message: mm/pgtable-generic.c:42: bad pud 00000000743d215d(84000001400000e7) We can tell that pud_clear_bad is called by pud_none_or_clear_bad in unuse_pud_range() by ftrace. And therefore the HugeTLB pages will never be freed because we lost it from page table. We can skip HugeTLB pages for unuse_vma to fix it.

Affected products

Linux kernel: from 2.6.36 before 5.4.285; from 5.5 before 5.10.228; from 5.11 before 5.15.169; from 5.16 before 6.1.114; from 6.2 before 6.6.58; from 6.7 before 6.11.5 — fixed in 5.10.228, 5.15.169, 5.4.285, 6.1.114, 6.11.5, 6.6.58

How to fix

Upgrade to a fixed version: Linux kernel 5.10.228, 5.15.169, 5.4.285, 6.1.114. Check the vendor advisory for mitigations.

References

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