Resource Injection Affecting kernel-rt-doc package, versions *


Severity

Recommended
0.0
medium
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.04% (11th percentile)

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  • Snyk IDSNYK-CENTOS7-KERNELRTDOC-7524898
  • published17 Jul 2024
  • disclosed12 Jul 2024

Introduced: 12 Jul 2024

CVE-2024-40950  (opens in a new tab)
CWE-99  (opens in a new tab)
First added by Snyk

How to fix?

There is no fixed version for Centos:7 kernel-rt-doc.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-doc package and not the kernel-rt-doc package as distributed by Centos. See How to fix? for Centos:7 relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

mm: huge_memory: fix misused mapping_large_folio_support() for anon folios

When I did a large folios split test, a WARNING "[ 5059.122759][ T166] Cannot split file folio to non-0 order" was triggered. But the test cases are only for anonmous folios. while mapping_large_folio_support() is only reasonable for page cache folios.

In split_huge_page_to_list_to_order(), the folio passed to mapping_large_folio_support() maybe anonmous folio. The folio_test_anon() check is missing. So the split of the anonmous THP is failed. This is also the same for shmem_mapping(). We'd better add a check for both. But the shmem_mapping() in __split_huge_page() is not involved, as for anonmous folios, the end parameter is set to -1, so (head[i].index >= end) is always false. shmem_mapping() is not called.

Also add a VM_WARN_ON_ONCE() in mapping_large_folio_support() for anon mapping, So we can detect the wrong use more easily.

THP folios maybe exist in the pagecache even the file system doesn't support large folio, it is because when CONFIG_TRANSPARENT_HUGEPAGE is enabled, khugepaged will try to collapse read-only file-backed pages to THP. But the mapping does not actually support multi order large folios properly.

Using /sys/kernel/debug/split_huge_pages to verify this, with this patch, large anon THP is successfully split and the warning is ceased.

CVSS Scores

version 3.1