tracing/synthetic: Fix races on freeing last_cmd

{
  "id": "8482afdd1fe2e29df023db85772d8a846852b75b1d053dff6023c558673aadc8",
  "url": "https://osv.dev/vulnerability/CVE-2023-53478",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "tracing/synthetic: Fix races on freeing last_cmd",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: tracing/synthetic: Fix races on freeing last_cmd Currently, the \"last_cmd\" variable can be accessed by multiple processes asynchronously when multiple users manipulate synthetic_events node at the same time, it could lead to use-after-free or double-free. This patch add \"lastcmd_mutex\" to prevent \"last_cmd\" from being accessed asynchronously. ================================================================ It's easy to reproduce in the KASAN environment by running the two scripts below in different shells. script 1: while : do echo -n -e '\\x88' > /sys/kernel/tracing/synthetic_events done script 2: while : do echo -n -e '\\xb0' > /sys/kernel/tracing/synthetic_events done ================================================================ double-free scenario: process A process B ------------------- --------------- 1.kstrdup last_cmd 2.free last_cmd 3.free last_cmd(double-free) ================================================================ use-after-free scenario: process A process B ------------------- --------------- 1.kstrdup last_cmd 2.free last_cmd 3.tracing_log_err(use-after-free) ================================================================ Appendix 1. KASAN report double-free: BUG: KASAN: double-free in kfree+0xdc/0x1d4 Free of addr ***** by task sh/4879 Call trace: ... kfree+0xdc/0x1d4 create_or_delete_synth_event+0x60/0x1e8 trace_parse_run_command+0x2bc/0x4b8 synth_events_write+0x20/0x30 vfs_write+0x",
    "evidence": "osv:CVE-2023-53478",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.24",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.2.11",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2023-53478",
      "aliases": [
        "CVE-2023-53478"
      ],
      "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": [
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                {
                  "fixed": "9fe183f659a2704255e5d84f6ae308c234a113ec"
                },
                {
                  "fixed": "8826d9e7bd51e7656f78baa4472e8e2f5e7069f0"
                },
                {
                  "fixed": "4ccf11c4e8a8e051499d53a12f502196c97a758e"
                }
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53478.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.18.0"
                },
                {
                  "fixed": "6.1.24"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.2.11"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2023-53478.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.236387514Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/4ccf11c4e8a8e051499d53a12f502196c97a758e",
        "https://git.kernel.org/stable/c/8826d9e7bd51e7656f78baa4472e8e2f5e7069f0",
        "https://git.kernel.org/stable/c/9fe183f659a2704255e5d84f6ae308c234a113ec",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/53xxx/CVE-2023-53478.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2023-53478",
        "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/2023/53xxx/CVE-2023-53478.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2023-53478",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 489363,
  "published_at": "2025-10-01T11:42:47.185+00:00"
}