sched_ext: Fix scx_enable() crash on helper kthread creation failure

{
  "id": "1d84c1f5b93e97409d56e8a39dbcef16e7ac423a042e94b47861c9340184030a",
  "url": "https://osv.dev/vulnerability/CVE-2025-40260",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "sched_ext: Fix scx_enable() crash on helper kthread creation failure",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix scx_enable() crash on helper kthread creation failure A crash was observed when the sched_ext selftests runner was terminated with Ctrl+\\ while test 15 was running: NIP [c00000000028fa58] scx_enable.constprop.0+0x358/0x12b0 LR [c00000000028fa2c] scx_enable.constprop.0+0x32c/0x12b0 Call Trace: scx_enable.constprop.0+0x32c/0x12b0 (unreliable) bpf_struct_ops_link_create+0x18c/0x22c __sys_bpf+0x23f8/0x3044 sys_bpf+0x2c/0x6c system_call_exception+0x124/0x320 system_call_vectored_common+0x15c/0x2ec kthread_run_worker() returns an ERR_PTR() on failure rather than NULL, but the current code in scx_alloc_and_add_sched() only checks for a NULL helper. Incase of failure on SIGQUIT, the error is not handled in scx_alloc_and_add_sched() and scx_enable() ends up dereferencing an error pointer. Error handling is fixed in scx_alloc_and_add_sched() to propagate PTR_ERR() into ret, so that scx_enable() jumps to the existing error path, avoiding random dereference on failure.",
    "evidence": "osv:CVE-2025-40260",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.17.10",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-40260",
      "aliases": [
        "CVE-2025-40260"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "introduced": "bff3b5aec1b727b620adc7c47085592802390125"
                },
                {
                  "fixed": "625e173e2a59b6cf6cbfb51c0a6bea47f3861eab"
                },
                {
                  "fixed": "7b6216baae751369195fa3c83d434d23bcda406a"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40260.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.16.0"
                },
                {
                  "fixed": "6.17.10"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-40260.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:21.264382582Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/625e173e2a59b6cf6cbfb51c0a6bea47f3861eab",
        "https://git.kernel.org/stable/c/7b6216baae751369195fa3c83d434d23bcda406a",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/40xxx/CVE-2025-40260.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-40260",
        "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/2025/40xxx/CVE-2025-40260.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-40260",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 487416,
  "published_at": "2025-12-04T16:08:20.59+00:00"
}