{"id":"CVE-2026-93181","state":"PUBLISHED","title":"perf/x86/intel/uncore: Fix uncore_box ref/unref ordering","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/x86/intel/uncore: Fix uncore_box ref/unref ordering\n\nIn uncore_event_cpu_online(), uncore_box_ref() was called before\nuncore_change_context().  uncore_box_ref() gates on box->cpu >= 0,\nbut box->cpu is still -1 at that point because uncore_change_context()\nhas not run yet.  As a result, the box is never initialized on the\nfirst CPU to come online in a die, leaving it permanently\nuninitialized in the single-CPU-per-die case.\n\nThus, box->refcnt is one count below the true value, and in the CPU\noffline path, the box will be torn down on the second-to-last CPU.\n\nIn uncore_event_cpu_offline(), uncore_box_unref() was called after\nuncore_change_context(), so box->cpu is already -1 when the collector\nCPU goes offline, which prevents it from tearing down the box.\n\nFix by swapping the call order in both paths so that\nuncore_box_{ref,unref}() runs at the point where box->cpu reflects\nthe correct context.\n\nMove allocate_boxes() out of uncore_box_ref() to enable this\nreordering.","publishedAt":"2026-09-17T16:12:08.716Z","updatedAt":"2026-10-21T12:52:12.996Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"c74443d92f68f07c03ae242ced554b749e6c6736","status":"affected","lessThan":"3cfd351602e6704cce9bc766a974afb9f745d44b","versionType":"git"},{"version":"c74443d92f68f07c03ae242ced554b749e6c6736","status":"affected","lessThan":"64aa1bb4017d598828c6d8cd718f43daf2a83375","versionType":"git"},{"version":"c74443d92f68f07c03ae242ced554b749e6c6736","status":"affected","lessThan":"174f0582e38abe03b88e15f04bfe58490f88cb19","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/events/intel/uncore.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/events/intel/uncore.c"]}],"references":["https://git.kernel.org/stable/c/3cfd351602e6704cce9bc766a974afb9f745d44b","https://git.kernel.org/stable/c/64aa1bb4017d598828c6d8cd718f43daf2a83375","https://git.kernel.org/stable/c/174f0582e38abe03b88e15f04bfe58490f88cb19"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:34.582Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/93xxx/CVE-2026-93181.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-93181","state":"PUBLISHED","datePublished":"2026-09-17T16:12:08.716Z","dateUpdated":"2026-10-21T12:52:12.996Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-17T16:02:15.091Z"},"containers":{"cna":{"title":"perf/x86/intel/uncore: Fix uncore_box ref/unref ordering","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nperf/x86/intel/uncore: Fix uncore_box ref/unref ordering\n\nIn uncore_event_cpu_online(), uncore_box_ref() was called before\nuncore_change_context().  uncore_box_ref() gates on box->cpu >= 0,\nbut box->cpu is still -1 at that point because uncore_change_context()\nhas not run yet.  As a result, the box is never initialized on the\nfirst CPU to come online in a die, leaving it permanently\nuninitialized in the single-CPU-per-die case.\n\nThus, box->refcnt is one count below the true value, and in the CPU\noffline path, the box will be torn down on the second-to-last CPU.\n\nIn uncore_event_cpu_offline(), uncore_box_unref() was called after\nuncore_change_context(), so box->cpu is already -1 when the collector\nCPU goes offline, which prevents it from tearing down the box.\n\nFix by swapping the call order in both paths so that\nuncore_box_{ref,unref}() runs at the point where box->cpu reflects\nthe correct context.\n\nMove allocate_boxes() out of uncore_box_ref() to enable this\nreordering."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"c74443d92f68f07c03ae242ced554b749e6c6736","status":"affected","lessThan":"3cfd351602e6704cce9bc766a974afb9f745d44b","versionType":"git"},{"version":"c74443d92f68f07c03ae242ced554b749e6c6736","status":"affected","lessThan":"64aa1bb4017d598828c6d8cd718f43daf2a83375","versionType":"git"},{"version":"c74443d92f68f07c03ae242ced554b749e6c6736","status":"affected","lessThan":"174f0582e38abe03b88e15f04bfe58490f88cb19","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/events/intel/uncore.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.11","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/events/intel/uncore.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/3cfd351602e6704cce9bc766a974afb9f745d44b"},{"url":"https://git.kernel.org/stable/c/64aa1bb4017d598828c6d8cd718f43daf2a83375"},{"url":"https://git.kernel.org/stable/c/174f0582e38abe03b88e15f04bfe58490f88cb19"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-21T12:52:12.996Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.11","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}