crash: fix crashkernel resource shrink

{
  "id": "94970185c9e6525e09cedd7c13ff37591096e713bd29ddbfe384cc5de74ca5ef",
  "url": "https://osv.dev/vulnerability/CVE-2025-68198",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "crash: fix crashkernel resource shrink",
    "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 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 Call Trace: ? __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 This happens because __crash_shrink_memory()/kernel/crash_core",
    "evidence": "osv:CVE-2025-68198",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.6.118",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.59",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.17.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-68198",
      "aliases": [
        "CVE-2025-68198"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "16c6006af4d4e70ecef93977a5314409d931020b"
                },
                {
                  "fixed": "f01f9c348d76d40bf104a94449e3ce4057fdefee"
                },
                {
                  "fixed": "f89c5e7077f63e45e8ba5a77b7cf0803130367e6"
                },
                {
                  "fixed": "a2bd247f8c6c5ac3f0ba823a2fffd77bb9cdf618"
                },
                {
                  "fixed": "00fbff75c5acb4755f06f08bd1071879c63940c5"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-68198.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.5.0"
                },
                {
                  "fixed": "6.6.118"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.59"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.17.9"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-68198.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:47.953696332Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/00fbff75c5acb4755f06f08bd1071879c63940c5",
        "https://git.kernel.org/stable/c/a2bd247f8c6c5ac3f0ba823a2fffd77bb9cdf618",
        "https://git.kernel.org/stable/c/f01f9c348d76d40bf104a94449e3ce4057fdefee",
        "https://git.kernel.org/stable/c/f89c5e7077f63e45e8ba5a77b7cf0803130367e6",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/68xxx/CVE-2025-68198.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-68198",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/68xxx/CVE-2025-68198.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-68198",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 515827,
  "published_at": "2025-12-16T13:48:26.998+00:00"
}