---
id: CVE-2026-74518
title: 'mm/hugetlb: fix list corruption in allocate_file_region_entries()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mm/hugetlb: fix list corruption in allocate_file_region_entries()

  allocate_file_region_entries() tops up resv->region_cache with freshly
  allocated file_region descript…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f <
    01b8569233e47693d6ff7efa96d9854c55f936fc
  - >-
    Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f <
    9c5fdffc5e1ce84403c58289ee72697051803bf7
  - >-
    Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f <
    f3e54f6a5e1681f83d13e8716bc92ef5ecf121d3
  - >-
    Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f <
    62e1c2741a4d923d9854efd5927a6212aad7a187
  - >-
    Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f <
    587a0accc2b4fccc5cf7baf0fe34e50efde51f9c
  - >-
    Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f <
    126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df
  - >-
    Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f <
    ac1bb7fd45088d0db57a22ce7729f258ebd63cf5
  - >-
    Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f <
    dd9623f58ec702a07b2d67179d6fcea79c52231a
  - Linux 5.10
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T18:58:55.418677Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:05:52.396Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-74518'
references:
  - url: 'https://git.kernel.org/stable/c/01b8569233e47693d6ff7efa96d9854c55f936fc'
  - url: 'https://git.kernel.org/stable/c/9c5fdffc5e1ce84403c58289ee72697051803bf7'
  - url: 'https://git.kernel.org/stable/c/f3e54f6a5e1681f83d13e8716bc92ef5ecf121d3'
  - url: 'https://git.kernel.org/stable/c/62e1c2741a4d923d9854efd5927a6212aad7a187'
  - url: 'https://git.kernel.org/stable/c/587a0accc2b4fccc5cf7baf0fe34e50efde51f9c'
  - url: 'https://git.kernel.org/stable/c/126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df'
  - url: 'https://git.kernel.org/stable/c/ac1bb7fd45088d0db57a22ce7729f258ebd63cf5'
  - url: 'https://git.kernel.org/stable/c/dd9623f58ec702a07b2d67179d6fcea79c52231a'
tags:
  - cve.org
epss: 0.00126
epssPercentile: 0.02029
ingestedAt: '2026-10-16T19:46:24.349Z'
---

## Overview

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

mm/hugetlb: fix list corruption in allocate_file_region_entries()

allocate_file_region_entries() tops up resv->region_cache with freshly
allocated file_region descriptors.  The allocation uses GFP_KERNEL, so
resv->lock is dropped around it: the new entries are gathered on a
stack-local list head, allocated_regions, and spliced into
resv->region_cache once the lock is re-acquired.

The splice used list_splice(), which moves the entries but does not
re-initialize the source head, so allocated_regions is left pointing at an
entry that now lives on resv->region_cache.  The top-up runs in a while
loop that re-checks the cache deficit after re-acquiring the lock.  For a
shared mapping the resv_map is shared by every mapper of the hugetlbfs
inode, so a concurrent region_chg()/region_add()/region_del() on the same
resv_map can consume cache entries during the unlocked window and force a
second iteration.  That iteration calls list_add() on the stale head and
corrupts the list; with CONFIG_DEBUG_LIST the __list_add_valid() check
trips:

  list_add corruption. next->prev should be prev (ffffc900011ff7f8),
  but was ffff88814c281460. (next=ffff88814c545640).
  kernel BUG at lib/list_debug.c:31!
   allocate_file_region_entries+0x191/0x420
   region_chg+0x267/0x300
   hugetlb_reserve_pages+0x387/0xc80
   hugetlbfs_file_mmap+0x2ce/0x3f0
   mmap_region+0x1348/0x1a80
   do_mmap+0x85e/0xb90
   vm_mmap_pgoff+0x18c/0x330
   ksys_mmap_pgoff+0x2a1/0x3e0
   do_syscall_64+0xd7/0x420

Without CONFIG_DEBUG_LIST the bad list_add() silently links a kernel-stack
address into resv->region_cache, leading to later use-after-free.

This was observed as a real host panic on a dense KVM host where a QEMU
guest-RAM hugetlbfs file was mapped MAP_SHARED by both QEMU and a separate
SPDK/DPDK vhost-user target, generating concurrent region_* traffic on one
shared resv_map.

Use list_splice_init() so the source head is re-initialized empty after
each splice, making the retry loop safe.

## Affected

- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 01b8569233e47693d6ff7efa96d9854c55f936fc`
- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 9c5fdffc5e1ce84403c58289ee72697051803bf7`
- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < f3e54f6a5e1681f83d13e8716bc92ef5ecf121d3`
- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 62e1c2741a4d923d9854efd5927a6212aad7a187`
- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 587a0accc2b4fccc5cf7baf0fe34e50efde51f9c`
- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df`
- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < ac1bb7fd45088d0db57a22ce7729f258ebd63cf5`
- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < dd9623f58ec702a07b2d67179d6fcea79c52231a`
- `Linux 5.10`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.