ftrace: fork: Initialize function graph state before copy_exec_state()

{
  "id": "7568c86cd906ec79d7b04aa958e33d7db25024369aa88d019ca9f1ba5f6e2b37",
  "url": "https://osv.dev/vulnerability/CVE-2026-97937",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ftrace: fork: Initialize function graph state before copy_exec_state()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ftrace: fork: Initialize function graph state before copy_exec_state() dup_task_struct() copies the parent's task_struct, including ret_stack. ftrace_graph_init_task() clears the copied function graph state, but it currently runs after copy_exec_state(). For non-CLONE_VM forks, copy_exec_state() allocates a new task_exec_state. If that allocation fails, copy_process() reaches bad_fork_free and free_task() calls ftrace_graph_exit_task(). Since the child still carries the parent's ret_stack pointer, the unwind frees the parent's active function graph return stack. The parent subsequently accesses freed memory from function_graph_enter_regs(). KASAN reports: [ 22.190920] ================================================================== [ 22.195899] BUG: KASAN: slab-use-after-free in function_graph_enter_regs+0xa76/0xb90 [ 22.200747] Write of size 8 at addr ff110000054dc0a8 by task repro/1 [ 22.205134] [ 22.210770] CPU: 0 UID: 0 PID: 1 Comm: repro Not tainted 7.2.0-07732-g9328b3b03bdc-dirty #3 PREEMPT(lazy) [ 22.212576] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 22.213750] Call Trace: [ 22.215271] [ 22.216242] ? ftrace_stub_direct_tramp+0x10/0x10 [ 22.217774] dump_stack_lvl+0x4e/0x70 [ 22.220531] print_report+0x157/0x4b4 [ 22.223202] ? fixup_red_left+0x9/0x30 [ 22.224407] ? complete_report_info+0x83/0x110 [ 22.226679] ? function_graph_enter_regs+0xa76/0xb90 [ ",
    "evidence": "osv:CVE-2026-97937",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.2.7",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-97937",
      "aliases": [
        "CVE-2026-97937"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "6b1c66c9cca99bf00386481c7b2aa7394c26d8b8"
                },
                {
                  "fixed": "1fadebbbf31f65beba353fa9d1373bf183e03fed"
                },
                {
                  "fixed": "08cacffeef8f64f1a222c93467ca84f24a46c953"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97937.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "7.2.0"
                },
                {
                  "fixed": "7.2.7"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97937.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:25.605578191Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/08cacffeef8f64f1a222c93467ca84f24a46c953",
        "https://git.kernel.org/stable/c/1fadebbbf31f65beba353fa9d1373bf183e03fed",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97937.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-97937",
        "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/2026/97xxx/CVE-2026-97937.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-97937",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 492197,
  "published_at": "2026-09-25T10:22:51.075+00:00"
}