rseq: Prevent hard lockup on granted time slice extension

{
  "id": "dc2a6ea820dbed61a80c129234603619df83a70c411083d9439fbc17cd3260a4",
  "url": "https://osv.dev/vulnerability/CVE-2026-74749",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "rseq: Prevent hard lockup on granted time slice extension",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: rseq: Prevent hard lockup on granted time slice extension __exit_to_user_mode_loop() invokes rseq_grant_timeslice_extension() with interrupts enabled. If the extension is granted it invokes hrtimer_rearm_deferred_tif() to ensure that a pending deferred hrtimer rearm is handled before exiting to user space. Though this invokes __hrtimer_rearm_deferred() which expects to be invoked with interrupts disabled as it takes hrtimer_cpu_base::lock with raw_spin_lock(). That's a livelock waiting to happen and caught by lockdep: WARNING: ./include/linux/hrtimer_rearm.h:17 at irqentry_exit, CPU#1: slice_test WARNING: inconsistent lock state inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage. Prevent this by disabling interrupts around the invocation of hrtimer_rearm_deferred_tif() in rseq_grant_timeslice_extension(). [ tglx: Massaged change log ]",
    "evidence": "osv:CVE-2026-74749",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.1.10",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-74749",
      "aliases": [
        "CVE-2026-74749"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "15dd3a9488557d3e6ebcecacab79f4e56b69ab54"
                },
                {
                  "fixed": "8bbf4405050bc4f98be68082a20efa081ea8ad9b"
                },
                {
                  "fixed": "ada54c2ba652348c590d1ace6a2f4ff77cbbf809"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74749.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "7.1.0"
                },
                {
                  "fixed": "7.1.10"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74749.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.455096967Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/8bbf4405050bc4f98be68082a20efa081ea8ad9b",
        "https://git.kernel.org/stable/c/ada54c2ba652348c590d1ace6a2f4ff77cbbf809",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74749.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-74749",
        "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/2026/74xxx/CVE-2026-74749.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-74749",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 493079,
  "published_at": "2026-08-26T14:36:57.763+00:00"
}