{"id":"CVE-2026-89460","revision":null,"records":[{"revision":"8af87f650f8d44c19a8f4fd66d75c9d3","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-89460","aliases":[],"title":"s390/cpum_cf: Handle CPU hotplug via prepare/dead callbacks","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/cpum_cf: Handle CPU hotplug via prepare/dead callbacks\n\nThe command 'perf stat -e cycles -- <command>' crashes the kernel\nwhen CPUs are hotplug added during that run.\n\nRoot cause is the allocation of struct cpu_cf_events at first\nevent initialization. The allocation is dynamic and the first\nevent that has task context creates such a structure for\neach online CPU. This is not sufficient. CPUs may be offline\nduring event creation and can be set online during the\nperf run time. For example commands\n\n # echo 0 > /sys/devices/system/cpu/cpu1/online\n # perf stat -e cycles -i -- stress-ng -t10s --matrix X\n # sleep 1\n # echo 1 > /sys/devices/system/cpu/cpu1/online\n\ncreate an event for CPUs 0,2-X. Since the events are created with\ntask-context, the scheduler will eventually schedule the program\non CPU1. This CPU has not created and initialized any per\nCPU event infrastructure as that CPU was not online at the time\nof the perf invocation. Thus when the scheduler runs stress-ng\non CPU1, the function cpumf_pmu_add() refers to a NULL pointer:\n\n struct cpu_cf_events *cpuhw = this_cpu_cfhw();\n\nThis function call is invoked after the task stress-ng has been\nmade runnable on CPU1. And this_cpu_cfhw() returns NULL.\n\nThe result is a panic:\nUnable to handle kernel pointer dereference in virtual kernel address space\nFailing address: 0000000000000000 TEID: 0000000000000483\n....\nKrnl PSW : 0404d00180000000 000003ef8291fd0c (cpumf_pmu_add+0x3c/0x80)\n....\nCall Trace:\n [<000003ef8291fd0c>] cpumf_pmu_add+0x3c/0x80\n [<000003ef82bb5e3e>] event_sched_in+0xae/0x190\n [<000003ef82bb60d6>] merge_sched_in+0x1b6/0x390\n [<000003ef82bb65b8>] visit_groups_merge.constprop.0.isra.0+0x308/0x5b0\n [<000003ef82bb689a>] pmu_groups_sched_in+0x3a/0x50\n [<000003ef82bb6a30>] ctx_sched_in+0x180/0x260\n [<000003ef82bb780c>] perf_event_context_sched_in+0x11c/0x2d0\n [<000003ef82bb79ee>] __perf_event_task_sched_in+0x2e/0xc0\n [<000003ef82994834>] finish_task_switch.isra.0+0x1a4/0x250\n....\nLast Breaking-Event-Address:\n [<000003ef8291f1d8>] this_cpu_cfhw+0x38/0x40\n\nThe issue arises only in per-task context when the CPUMF facility is\nused and the scheduler picks a random CPU for such a process to run on.\nThe scheduler enables the CPUMF infrastructure via PMU callback\nfunctions pmu::add() and pmu::del().\n\nIntroduce a CPU hotplug prepare/dead callback pair which creates and\nremoves the per CPU counter data while the CPU is offline. Count the\nusers which track every CPU (cpu == -1), that is perf_event_open()\nevents with task context and /dev/hwctr device sessions, in the new\ncounter cpu_cf_root::tskcnt, protected by pmc_reserve_mutex.\nThis ensures the infrastructure is available when\nnew CPU is selected to run the per-task context process.\n\nIn cpum_cf_free_root() and cpum_cf_free_cpu() ensure the reference\npointer to data structures is set to NULL before the data is freed\nto prevent interrupt handlers to access stale data.\n\n[gor@linux.ibm.com: change commit message]","state":0,"publishedAt":"2026-09-11T19:43:22.664+00:00","modifiedAt":"2026-10-19T08:47:09.624+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"arch/s390/kernel/perf_cpum_cf.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"9b9cf3c77e7e090b30657b3d2c288deb58dfb4f2\",\n                            \"lessThan\": \"991be92489bc7b1b6e7903debb96bd58c892dee4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9b9cf3c77e7e090b30657b3d2c288deb58dfb4f2\",\n                            \"lessThan\": \"777d040c2f91d8d929b4a32333dfe4102b27caea\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9b9cf3c77e7e090b30657b3d2c288deb58dfb4f2\",\n                            \"lessThan\": \"dcce7a06ea690d5cf46a705a9b74cf0398ac091f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9b9cf3c77e7e090b30657b3d2c288deb58dfb4f2\",\n                            \"lessThan\": \"71d46de9153e067c63a15f3b00e6364e1c0230f8\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"9b9cf3c77e7e090b30657b3d2c288deb58dfb4f2\",\n                            \"lessThan\": \"337bd95507a16063687cfc286ea90de5cca48c37\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"arch/s390/kernel/perf_cpum_cf.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.5\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.5\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.157\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.109\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.50\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.4\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/991be92489bc7b1b6e7903debb96bd58c892dee4","https://git.kernel.org/stable/c/777d040c2f91d8d929b4a32333dfe4102b27caea","https://git.kernel.org/stable/c/dcce7a06ea690d5cf46a705a9b74cf0398ac091f","https://git.kernel.org/stable/c/71d46de9153e067c63a15f3b00e6364e1c0230f8","https://git.kernel.org/stable/c/337bd95507a16063687cfc286ea90de5cca48c37"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89460","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-89460","identifiers":["CVE-2026-89460"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-09T05:02:23.3236319+00:00","complete":true,"records":1769,"lastAttemptAt":"2026-11-09T05:02:23.3236319+00:00","lastSuccessAt":"2026-11-09T05:02:23.479545+00:00","error":null,"lastVerifiedAt":"2026-11-09T05:02:23.4795489+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-24e6fde7b744113daefb8f6135035fb8a5c69c9617c9c0d40574a0376532ffd3-61bf15172f364246efc204ad9b25e3f89710939e13c23b3efb3d009b5fdad808","complete":true,"records":421290,"lastAttemptAt":"2026-11-09T05:02:14.5383867+00:00","lastSuccessAt":"2026-11-09T05:02:14.5253969+00:00","error":null,"lastVerifiedAt":"2026-11-09T05:02:14.5383867+00:00","snapshotPublishedAt":"2026-11-09T04:29:38+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-4f2cebce00d8473081b28b769c5ae383","complete":false,"records":13654,"lastAttemptAt":"2026-11-09T05:14:17.7698071+00:00","lastSuccessAt":"2026-11-09T05:14:17.765+00:00","error":"8 identifier lookups failed; latest failures include HTTP 403. Other identifiers were checked independently.","lastVerifiedAt":"2026-11-09T05:14:17.765+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13657,"expectedIdentifiers":13706,"failedIdentifiers":8},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-09T05:02:23.3236319+00:00","complete":true,"records":1096,"lastAttemptAt":"2026-11-09T05:02:23.3236319+00:00","lastSuccessAt":"2026-11-09T05:02:23.4802497+00:00","error":null,"lastVerifiedAt":"2026-11-09T05:02:23.4802499+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-5a44a451442747cb81d83104fe1e7771","complete":true,"records":13666,"lastAttemptAt":"2026-11-09T05:02:23.9456768+00:00","lastSuccessAt":"2026-11-09T02:08:52.274+00:00","error":null,"lastVerifiedAt":"2026-11-09T02:08:52.274+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13706,"expectedIdentifiers":13706,"failedIdentifiers":0},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-980593e6977a6d1b4fb1eed5a1ffe88a468736f89f0a06f710924ad59132c023","complete":true,"records":9914,"lastAttemptAt":"2026-11-09T05:02:15.1760519+00:00","lastSuccessAt":"2026-11-08T11:07:07.068788+00:00","error":null,"lastVerifiedAt":"2026-11-09T05:02:15.1760519+00:00","snapshotPublishedAt":"2026-11-08T11:02:46+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-fde804134ecdda0ddd5ff5c26ee1fff5a6fa659311f7ef2e51c6ad54964db0e2","complete":true,"records":1971,"lastAttemptAt":"2026-11-09T05:02:14.6871775+00:00","lastSuccessAt":"2026-11-06T19:03:17.0399903+00:00","error":null,"lastVerifiedAt":"2026-11-09T05:02:14.6871775+00:00","snapshotPublishedAt":"2026-11-06T18:17:57+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-f6d341f4320a5a0c059c28102ee651c3dd06abc87b84d2bafa4e2a823ec07d35","complete":true,"records":3056,"lastAttemptAt":"2026-11-09T05:02:23.2913664+00:00","lastSuccessAt":"2026-11-09T05:02:23.1539412+00:00","error":null,"lastVerifiedAt":"2026-11-09T05:02:23.2913664+00:00","snapshotPublishedAt":"2026-11-09T04:47:48+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-6a1c845b1938b1aa788f0e95c9ac8a8d5a1f07caed5d155840b0616b548c1455","complete":true,"records":231296,"lastAttemptAt":"2026-11-09T05:02:15.0730779+00:00","lastSuccessAt":"2026-11-09T04:03:49.859595+00:00","error":null,"lastVerifiedAt":"2026-11-09T05:02:15.0730779+00:00","snapshotPublishedAt":"2026-11-09T03:33:06+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}