crypto: zstd - fix double-free in per-CPU stream cleanup

{
  "id": "2d0ba557f4c829c2e4e600908873eb6e414c7c506f90b523aa35266dd5996214",
  "url": "https://osv.dev/vulnerability/CVE-2025-68262",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "crypto: zstd - fix double-free in per-CPU stream cleanup",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: crypto: zstd - fix double-free in per-CPU stream cleanup The crypto/zstd module has a double-free bug that occurs when multiple tfms are allocated and freed. The issue happens because zstd_streams (per-CPU contexts) are freed in zstd_exit() during every tfm destruction, rather than being managed at the module level. When multiple tfms exist, each tfm exit attempts to free the same shared per-CPU streams, resulting in a double-free. This leads to a stack trace similar to: BUG: Bad page state in process kworker/u16:1 pfn:106fd93 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x106fd93 flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff) page_type: 0xffffffff() raw: 0017ffffc0000000 dead000000000100 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: nonzero entire_mapcount Modules linked in: ... CPU: 3 UID: 0 PID: 2506 Comm: kworker/u16:1 Kdump: loaded Tainted: G B Hardware name: ... Workqueue: btrfs-delalloc btrfs_work_helper Call Trace: dump_stack_lvl+0x5d/0x80 bad_page+0x71/0xd0 free_unref_page_prepare+0x24e/0x490 free_unref_page+0x60/0x170 crypto_acomp_free_streams+0x5d/0xc0 crypto_acomp_exit_tfm+0x23/0x50 crypto_destroy_tfm+0x60/0xc0 ... Change the lifecycle management of zstd_streams to free the streams only once during module cleanup.",
    "evidence": "osv:CVE-2025-68262",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.17.12",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-68262",
      "aliases": [
        "CVE-2025-68262"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                {
                  "fixed": "dc0f4509b0ed5d82bef78e058db0ac4df04d0695"
                },
                {
                  "fixed": "e983feaa79de1e46c9087fb9f02fedb0e5397ce6"
                },
                {
                  "fixed": "48bc9da3c97c15f1ea24934bcb3b736acd30163d"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-68262.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.17.0"
                },
                {
                  "fixed": "6.17.12"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.18.0"
                },
                {
                  "fixed": "6.18.1"
                }
              ]
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-68262.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:25.471320539Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/48bc9da3c97c15f1ea24934bcb3b736acd30163d",
        "https://git.kernel.org/stable/c/dc0f4509b0ed5d82bef78e058db0ac4df04d0695",
        "https://git.kernel.org/stable/c/e983feaa79de1e46c9087fb9f02fedb0e5397ce6",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/68xxx/CVE-2025-68262.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-68262",
        "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-2025-68262.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-68262",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 491728,
  "published_at": "2025-12-16T14:45:04.198+00:00"
}