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GHSA-4MG4-96G4-2J54

Vulnerability from github – Published: 2026-09-25 12:31 – Updated: 2026-09-25 12:31

Details

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/ -- ' 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.

[hca@linux.ibm.com: fixup error path in pai_init()]

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{
  "affected": [],
  "aliases": [
    "CVE-2026-97526"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-25T11:17:02Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/pai: Support CPU hotplug for PMU PAI\n\nThe command \u0027perf stat -e pai_crypto/CRYPTO_ALL/ -- \u003ccommand\u003e\u0027\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 \u003e /sys/devices/system/cpu/cpu1/online\n # perf stat -e cycles -i -- stress-ng -t10s --matrix X\n # sleep 1\n # echo 1 \u003e /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-\u003emapptr;\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()]",
  "id": "GHSA-4mg4-96g4-2j54",
  "modified": "2026-09-25T12:31:22Z",
  "published": "2026-09-25T12:31:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-97526"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/706e2bf330144995d123dccf32aaf1981ce5abc2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9ecc4d033879f7761f2df07e20cd2fbec00fd90b"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-97526 (GCVE-0-2026-97526)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:21 – Updated: 2026-09-25 10:21

Title

s390/pai: Support CPU hotplug for PMU PAI

Summary

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. [hca@linux.ibm.com: fixup error path in pai_init()]

Severity

No CVSS data available.

Assigner

Linux mitre root

References

2 references

URL	Tags
https://git.kernel.org/stable/c/706e2bf330144995d…
https://git.kernel.org/stable/c/9ecc4d033879f7761…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 9f66572f2889a5e72a9d7e17787e52f03b1f7bd8 , < 706e2bf330144995d123dccf32aaf1981ce5abc2 (git) Affected: 9f66572f2889a5e72a9d7e17787e52f03b1f7bd8 , < 9ecc4d033879f7761f2df07e20cd2fbec00fd90b (git)
Linux	Linux	Affected: 6.11 Unaffected: 0 , < 6.11 (semver) Unaffected: 7.2.7 , ≤ 7.2.* (semver) Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "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",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "706e2bf330144995d123dccf32aaf1981ce5abc2",
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              "versionType": "git"
            },
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              "status": "affected",
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              "versionType": "git"
            }
          ]
        },
        {
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          "product": "Linux",
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.11"
            },
            {
              "lessThan": "6.11",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix"
            }
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                  "versionStartIncluding": "6.11",
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/pai: Support CPU hotplug for PMU PAI\n\nThe command \u0027perf stat -e pai_crypto/CRYPTO_ALL/ -- \u003ccommand\u003e\u0027\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 \u003e /sys/devices/system/cpu/cpu1/online\n # perf stat -e cycles -i -- stress-ng -t10s --matrix X\n # sleep 1\n # echo 1 \u003e /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-\u003emapptr;\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()]"
        }
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        "dateUpdated": "2026-09-25T10:21:28.923Z",
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        {
          "url": "https://git.kernel.org/stable/c/9ecc4d033879f7761f2df07e20cd2fbec00fd90b"
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      ],
      "title": "s390/pai: Support CPU hotplug for PMU PAI",
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    "datePublished": "2026-09-25T10:21:28.923Z",
    "dateReserved": "2026-09-24T16:01:01.152Z",
    "dateUpdated": "2026-09-25T10:21:28.923Z",
    "state": "PUBLISHED"
  },
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-4MG4-96G4-2J54

CVE-2026-97526 (GCVE-0-2026-97526)

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