{"id":"CVE-2026-68174","state":"PUBLISHED","title":"tracing: Fix union collision of module and refcnt for dynamic events","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Fix union collision of module and refcnt for dynamic events\n\nIn 'struct trace_event_call', the 'module' pointer and the 'refcnt'\natomic variable share the same memory space in a union. For dynamic\nevents, the union member is 'refcnt', 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 'call->module' evaluates to a\nsmall non-zero integer instead of NULL.\n\nWhen filtering or setting events for a specific module (e.g., writing\n':mod:<module>' to 'set_event'), the code in\n'__ftrace_set_clr_event_nolock()' and 'update_event_fields()' reads\n'call->module' directly without checking whether the event is dynamic.\nThis causes the kernel to treat the small integer (refcnt) as a\n'struct module' pointer, leading to a NULL/invalid pointer dereference\n(Oops) when dereferencing the module name.\n\nFix this by ensuring that the 'TRACE_EVENT_FL_DYNAMIC' flag is checked\nbefore treating 'call->module' as a valid pointer in these code paths.","publishedAt":"2026-08-10T11:59:44.417Z","updatedAt":"2026-08-17T05:00:15.155Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4c86bc531e60900053384867c082675bba82c29f","status":"affected","lessThan":"b6a4575f22925da7e6aa00171e9fc0e5029c0bc9","versionType":"git"},{"version":"4c86bc531e60900053384867c082675bba82c29f","status":"affected","lessThan":"43a23dfe0024afd3d2b0232e987d0292919a9b24","versionType":"git"},{"version":"4c86bc531e60900053384867c082675bba82c29f","status":"affected","lessThan":"b4eb07bde606c2096b24252be589e735eff6d413","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.14","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events.c"]}],"references":["https://git.kernel.org/stable/c/b6a4575f22925da7e6aa00171e9fc0e5029c0bc9","https://git.kernel.org/stable/c/43a23dfe0024afd3d2b0232e987d0292919a9b24","https://git.kernel.org/stable/c/b4eb07bde606c2096b24252be589e735eff6d413"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/68xxx/CVE-2026-68174.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-68174","state":"PUBLISHED","datePublished":"2026-08-10T11:59:44.417Z","dateUpdated":"2026-08-17T05:00:15.155Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-30T09:28:09.372Z"},"containers":{"cna":{"title":"tracing: Fix union collision of module and refcnt for dynamic events","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 'struct trace_event_call', the 'module' pointer and the 'refcnt'\natomic variable share the same memory space in a union. For dynamic\nevents, the union member is 'refcnt', 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 'call->module' evaluates to a\nsmall non-zero integer instead of NULL.\n\nWhen filtering or setting events for a specific module (e.g., writing\n':mod:<module>' to 'set_event'), the code in\n'__ftrace_set_clr_event_nolock()' and 'update_event_fields()' reads\n'call->module' directly without checking whether the event is dynamic.\nThis causes the kernel to treat the small integer (refcnt) as a\n'struct module' pointer, leading to a NULL/invalid pointer dereference\n(Oops) when dereferencing the module name.\n\nFix this by ensuring that the 'TRACE_EVENT_FL_DYNAMIC' flag is checked\nbefore treating 'call->module' as a valid pointer in these code paths."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4c86bc531e60900053384867c082675bba82c29f","status":"affected","lessThan":"b6a4575f22925da7e6aa00171e9fc0e5029c0bc9","versionType":"git"},{"version":"4c86bc531e60900053384867c082675bba82c29f","status":"affected","lessThan":"43a23dfe0024afd3d2b0232e987d0292919a9b24","versionType":"git"},{"version":"4c86bc531e60900053384867c082675bba82c29f","status":"affected","lessThan":"b4eb07bde606c2096b24252be589e735eff6d413","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.14","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/trace/trace_events.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/b6a4575f22925da7e6aa00171e9fc0e5029c0bc9"},{"url":"https://git.kernel.org/stable/c/43a23dfe0024afd3d2b0232e987d0292919a9b24"},{"url":"https://git.kernel.org/stable/c/b4eb07bde606c2096b24252be589e735eff6d413"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:00:15.155Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"6.18.42"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"7.1.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.14","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}