FKIE_CVE-2026-68174

Vulnerability from fkie_nvd - Published: 2026-08-10 13:20 - Updated: 2026-08-17 05:18
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: tracing: Fix union collision of module and refcnt for dynamic events In 'struct trace_event_call', the 'module' pointer and the 'refcnt' atomic variable share the same memory space in a union. For dynamic events, the union member is 'refcnt', which acts as an active reference counter. When a dynamic event (such as kprobe, uprobe, fprobe, eprobe, or wprobe) has a non-zero reference count (e.g. due to active event triggers or perf attachments), its 'call->module' evaluates to a small non-zero integer instead of NULL. When filtering or setting events for a specific module (e.g., writing ':mod:<module>' to 'set_event'), the code in '__ftrace_set_clr_event_nolock()' and 'update_event_fields()' reads 'call->module' directly without checking whether the event is dynamic. This causes the kernel to treat the small integer (refcnt) as a 'struct module' pointer, leading to a NULL/invalid pointer dereference (Oops) when dereferencing the module name. Fix this by ensuring that the 'TRACE_EVENT_FL_DYNAMIC' flag is checked before treating 'call->module' as a valid pointer in these code paths.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/43a23dfe0024afd3d2b0232e987d0292919a9b24
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b4eb07bde606c2096b24252be589e735eff6d413
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b6a4575f22925da7e6aa00171e9fc0e5029c0bc9
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/trace/trace_events.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "b6a4575f22925da7e6aa00171e9fc0e5029c0bc9",
              "status": "affected",
              "version": "4c86bc531e60900053384867c082675bba82c29f",
              "versionType": "git"
            },
            {
              "lessThan": "43a23dfe0024afd3d2b0232e987d0292919a9b24",
              "status": "affected",
              "version": "4c86bc531e60900053384867c082675bba82c29f",
              "versionType": "git"
            },
            {
              "lessThan": "b4eb07bde606c2096b24252be589e735eff6d413",
              "status": "affected",
              "version": "4c86bc531e60900053384867c082675bba82c29f",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/trace/trace_events.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.14"
            },
            {
              "lessThan": "6.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix union collision of module and refcnt for dynamic events\n\nIn \u0027struct trace_event_call\u0027, the \u0027module\u0027 pointer and the \u0027refcnt\u0027\natomic variable share the same memory space in a union. For dynamic\nevents, the union member is \u0027refcnt\u0027, which acts as an active\nreference counter.\n\nWhen a dynamic event (such as kprobe, uprobe, fprobe, eprobe, or\nwprobe) has a non-zero reference count (e.g. due to active event\ntriggers or perf attachments), its \u0027call-\u003emodule\u0027 evaluates to a\nsmall non-zero integer instead of NULL.\n\nWhen filtering or setting events for a specific module (e.g., writing\n\u0027:mod:\u003cmodule\u003e\u0027 to \u0027set_event\u0027), the code in\n\u0027__ftrace_set_clr_event_nolock()\u0027 and \u0027update_event_fields()\u0027 reads\n\u0027call-\u003emodule\u0027 directly without checking whether the event is dynamic.\nThis causes the kernel to treat the small integer (refcnt) as a\n\u0027struct module\u0027 pointer, leading to a NULL/invalid pointer dereference\n(Oops) when dereferencing the module name.\n\nFix this by ensuring that the \u0027TRACE_EVENT_FL_DYNAMIC\u0027 flag is checked\nbefore treating \u0027call-\u003emodule\u0027 as a valid pointer in these code paths."
    }
  ],
  "id": "CVE-2026-68174",
  "lastModified": "2026-08-17T05:18:18.927",
  "metrics": {},
  "published": "2026-08-10T13:20:04.213",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/43a23dfe0024afd3d2b0232e987d0292919a9b24"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b4eb07bde606c2096b24252be589e735eff6d413"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b6a4575f22925da7e6aa00171e9fc0e5029c0bc9"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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