Vulnerability-Lookup

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: 2026-10-19 09:08

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 CNA under the mitre root

CNA scorecard D 53/100 over 6641 records in the last 180 days details

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 , ≤ * (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": [
            {
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              "versionType": "git"
            },
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              "status": "affected",
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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            "arch/s390/kernel/perf_pai.c"
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          "vendor": "Linux",
          "versions": [
            {
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              "version": "6.11"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
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              "versionType": "original_commit_for_fix"
            }
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                  "vulnerable": true
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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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    "datePublished": "2026-09-25T10:21:28.923Z",
    "dateReserved": "2026-09-24T16:01:01.152Z",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
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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