{"cve":"CVE-2026-97526","nvd":{"published":"2026-09-25T11:17:02.767","modified":"2026-10-19T10:17:21.543","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/pai: Support CPU hotplug for PMU PAI\n\nThe command 'perf stat -e pai_crypto/CRYPTO_ALL/ -- <command>'\ncrashes the kernel when CPUs are hotplug added during that run.\n\nRoot cause is the missing allocation of per-CPU data structures\nfor that new CPU. 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\nCurrently without a CPU hotplug handler, that new CPU has no\nper-CPU data infrastructure. The scheduler runs PMU call back\nfunction pai_add() to install the PMU support for that CPU before\nthe task is being scheduled on that new CPU.\nIn pai_add() instructions\n\n    mp = this_cpu_ptr(pai_root[idx].mapptr);\n    cpump = mp->mapptr;\n\nreturn a NULL pointer and the result is a kernel panic as variable\ncpump is used inside that function.\n\nAdd CPU hotplug support for CPU add and delete and create\nthe necessary per-CPU data infrastructure during CPU hotplug\nadd processing. Same for CPU hotplug remove.\nThis is done when the CPU is offline to ensure the data structures\nare available when CPU is made online and tasks are scheduled on it.\n\n[hca@linux.ibm.com: fixup error path in pai_init()]","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/706e2bf330144995d123dccf32aaf1981ce5abc2","https://git.kernel.org/stable/c/9ecc4d033879f7761f2df07e20cd2fbec00fd90b"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:56:02.509636177+00:00"},"epss":{"cve":"CVE-2026-97526","score":0.00189,"percentile":0.0847,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}