CVE-2026-97526

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: s390/pai: Support CPU hotplug for PMU PAI The command 'perf stat -e pai_crypto/CRYPTO_ALL/ -- <command>' crashes the kernel when CPUs are hotplug added during that run. Root cause is the missing allocation of per-CPU data structures for that new CPU. The allocation is dynamic and the first event that has task context creates such a structure for each online CPU. This is not sufficient. CPUs may be offline during event creation and can be set online during the perf run time. For example commands # echo 0 > /sys/devices/system/cpu/cpu1/online # perf stat -e cycles -i -- stress-ng -t10s --matrix X # sleep 1 # echo 1 > /sys/devices/system/cpu/cpu1/online Currently without a CPU hotplug handler, that new CPU has no per-CPU data infrastructure. The scheduler runs PMU call back function pai_add() to install the PMU support for that CPU before the task is being scheduled on that new CPU. In pai_add() instructions mp = this_cpu_ptr(pai_root[idx].mapptr); cpump = mp->mapptr; return a NULL pointer and the result is a kernel panic as variable cpump is used inside that function. Add CPU hotplug support for CPU add and delete and create the necessary per-CPU data infrastructure during CPU hotplug add processing. Same for CPU hotplug remove. This is done when the CPU is offline to ensure the data structures are available when CPU is made online and tasks are scheduled on it. [[email protected]: fixup error path in pai_init()]

Severity

Not scored

CVSS score

Not available

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-09-25 11:17:02.767000

Last modified

2026-10-19 10:17:21.543000

View original CVE JSON

{
  "id": "CVE-2026-97526",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-09-25T11:17:02.767",
  "lastModified": "2026-10-19T10:17:21.543",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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[[email protected]: fixup error path in pai_init()]"
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "arch/s390/include/asm/pai.h",
            "arch/s390/kernel/perf_pai.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "9f66572f2889a5e72a9d7e17787e52f03b1f7bd8",
              "lessThan": "706e2bf330144995d123dccf32aaf1981ce5abc2",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "9f66572f2889a5e72a9d7e17787e52f03b1f7bd8",
              "lessThan": "9ecc4d033879f7761f2df07e20cd2fbec00fd90b",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "arch/s390/include/asm/pai.h",
            "arch/s390/kernel/perf_pai.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "6.11",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "6.11",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2.7",
              "lessThanOrEqual": "7.2.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.3",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/706e2bf330144995d123dccf32aaf1981ce5abc2",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9ecc4d033879f7761f2df07e20cd2fbec00fd90b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}