---
id: CVE-2025-68198
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  crash: fix crashkernel resource shrink

  When crashkernel is configured with a high reservation, shrinking its
  value below the low crashkernel reservation causes two iss…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  crash: fix crashkernel resource shrink

  When crashkernel is configured with a high reservation, shrinking its
  value below the low crashkernel reservation causes two iss…
severity: none
published: '2025-12-16'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T13:10:00.187'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-68198'
references:
  - url: 'https://git.kernel.org/stable/c/00fbff75c5acb4755f06f08bd1071879c63940c5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a2bd247f8c6c5ac3f0ba823a2fffd77bb9cdf618'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f01f9c348d76d40bf104a94449e3ce4057fdefee'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/f89c5e7077f63e45e8ba5a77b7cf0803130367e6'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00199
epssPercentile: 0.09062
ingestedAt: '2026-10-14T13:30:58.451Z'
---

## Overview

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

crash: fix crashkernel resource shrink

When crashkernel is configured with a high reservation, shrinking its
value below the low crashkernel reservation causes two issues:

1. Invalid crashkernel resource objects
2. Kernel crash if crashkernel shrinking is done twice

For example, with crashkernel=200M,high, the kernel reserves 200MB of high
memory and some default low memory (say 256MB).  The reservation appears
as:

cat /proc/iomem | grep -i crash
af000000-beffffff : Crash kernel
433000000-43f7fffff : Crash kernel

If crashkernel is then shrunk to 50MB (echo 52428800 >
/sys/kernel/kexec_crash_size), /proc/iomem still shows 256MB reserved:
af000000-beffffff : Crash kernel

Instead, it should show 50MB:
af000000-b21fffff : Crash kernel

Further shrinking crashkernel to 40MB causes a kernel crash with the
following trace (x86):

BUG: kernel NULL pointer dereference, address: 0000000000000038
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
<snip...>
Call Trace: <TASK>
? __die_body.cold+0x19/0x27
? page_fault_oops+0x15a/0x2f0
? search_module_extables+0x19/0x60
? search_bpf_extables+0x5f/0x80
? exc_page_fault+0x7e/0x180
? asm_exc_page_fault+0x26/0x30
? __release_resource+0xd/0xb0
release_resource+0x26/0x40
__crash_shrink_memory+0xe5/0x110
crash_shrink_memory+0x12a/0x190
kexec_crash_size_store+0x41/0x80
kernfs_fop_write_iter+0x141/0x1f0
vfs_write+0x294/0x460
ksys_write+0x6d/0xf0
<snip...>

This happens because __crash_shrink_memory()/kernel/crash_core.c
incorrectly updates the crashk_res resource object even when
crashk_low_res should be updated.

Fix this by ensuring the correct crashkernel resource object is updated
when shrinking crashkernel memory.

## Remediation

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