uprobes: Fix NULL pointer dereference in hprobe_expire()

{
  "id": "4d9b0a06733796e2339ea37b6638919ec524116aeb3f8fd34b05b2a693b5a02e",
  "url": "https://osv.dev/vulnerability/CVE-2026-74477",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "uprobes: Fix NULL pointer dereference in hprobe_expire()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: uprobes: Fix NULL pointer dereference in hprobe_expire() Forking a task that has a pending uretprobe can oops the kernel with a NULL pointer dereference in the clone() path: BUG: kernel NULL pointer dereference, address: 0000000000000018 Oops: 0002 [#1] SMP NOPTI RIP: 0010:hprobe_expire CR2: 0000000000000018 Call Trace: uprobe_copy_process copy_process kernel_clone __x64_sys_clone do_syscall_64 entry_SYSCALL_64_after_hwframe This was found on real hosts on Meta fleet. I've got the impression that this is what is happening: CPU 1 CPU 2 (traced task) ----- ------------------- hit uprobe, prepare_uretprobe(): hprobe LEASED, refcount >= 1 uprobe_unregister() put_uprobe(): refcount -> 0 fork() -> dup_utask() hprobe_expire(hprobe, true) try_get_uprobe() -> NULL get_uprobe(NULL) <-- Oops Only take the extra reference when the uprobe is non-NULL; a NULL means it is gone and is the correct value to return.",
    "evidence": "osv:CVE-2026-74477",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.44",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-74477",
      "aliases": [
        "CVE-2026-74477"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "dd1a7567784e2b1f80258be04f57bcfa82c997eb"
                },
                {
                  "fixed": "3bd35a5e272a1b7a3fb43acad9bdc599281b13fa"
                },
                {
                  "fixed": "06c275a6c0a953ef1d763d11a6891fcc69ae2ac0"
                },
                {
                  "fixed": "cc679d7a6303e84d769f2afcde1fc51c51f127cd"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74477.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.44"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.1.8"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74477.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:28.385480876Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/06c275a6c0a953ef1d763d11a6891fcc69ae2ac0",
        "https://git.kernel.org/stable/c/3bd35a5e272a1b7a3fb43acad9bdc599281b13fa",
        "https://git.kernel.org/stable/c/cc679d7a6303e84d769f2afcde1fc51c51f127cd",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74477.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-74477",
        "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-2026-74477.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-74477",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 495342,
  "published_at": "2026-08-15T12:27:11.938+00:00"
}