Vulnerability-Lookup

FKIE_CVE-2026-89991

Vulnerability from fkie_nvd - Published: 2026-09-16 11:17 - Updated: 2026-09-16 11:17

Severity

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix infinite loop in pcpu_freelist push with one possible CPU __pcpu_freelist_push() can loop forever when only one CPU is possible and an NMI re-enters pcpu_freelist_push() while the interrupted context holds that CPU's freelist lock. After the current-CPU fast path fails, the fallback loop walks cpu_possible_mask while skipping the current CPU. With CONFIG_SMP=n, or when an SMP kernel is limited to one possible CPU with nr_cpus=1 or possible_cpus=1, there are no other possible CPUs to examine. The loop therefore makes no lock acquisition attempt and can never make progress. The following stack was observed on a UP system: NMI context: pcpu_freelist_push free_htab_elem htab_map_delete_elem [perf-event BPF program] __perf_event_overflow perf_event_nmi_handler exc_nmi Interrupted context: __pcpu_freelist_push pcpu_freelist_push free_htab_elem htab_map_delete_elem [raw_tp/sys_enter BPF program] __bpf_trace_sys_enter do_syscall_64 raw_res_spin_lock() detects the same-CPU recursive acquisition and returns -EDEADLK, but the subsequent fallback loop has no candidate head on a system with one possible CPU. Restore the extra fallback head that existed before the rqspinlock conversion. Keep the current-CPU fast path, then try the other possible CPUs and finally the extra head. The additional head lets a push, which cannot fail without losing a preallocated element, make progress when the only per-CPU head is held by the interrupted context. Also check the extra head from the pop path so that nodes placed there can be reused.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/a24a146ae2cb5d9faeea96d10010fcb6579abe1f
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/a5b5e62baceff9e252c6535cf42a027d04f226cf
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/efebf6496685c93150df5bb0794363ae70c5f58a

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/percpu_freelist.c",
            "kernel/bpf/percpu_freelist.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a24a146ae2cb5d9faeea96d10010fcb6579abe1f",
              "status": "affected",
              "version": "f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb",
              "versionType": "git"
            },
            {
              "lessThan": "a5b5e62baceff9e252c6535cf42a027d04f226cf",
              "status": "affected",
              "version": "f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb",
              "versionType": "git"
            },
            {
              "lessThan": "efebf6496685c93150df5bb0794363ae70c5f58a",
              "status": "affected",
              "version": "f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/percpu_freelist.c",
            "kernel/bpf/percpu_freelist.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix infinite loop in pcpu_freelist push with one possible CPU\n\n__pcpu_freelist_push() can loop forever when only one CPU is possible\nand an NMI re-enters pcpu_freelist_push() while the interrupted context\nholds that CPU\u0027s freelist lock.\n\nAfter the current-CPU fast path fails, the fallback loop walks\ncpu_possible_mask while skipping the current CPU. With CONFIG_SMP=n, or\nwhen an SMP kernel is limited to one possible CPU with nr_cpus=1 or\npossible_cpus=1, there are no other possible CPUs to examine. The loop\ntherefore makes no lock acquisition attempt and can never make progress.\n\nThe following stack was observed on a UP system:\n\n  NMI context:\n    pcpu_freelist_push\n    free_htab_elem\n    htab_map_delete_elem\n    [perf-event BPF program]\n    __perf_event_overflow\n    perf_event_nmi_handler\n    exc_nmi\n\n  Interrupted context:\n    __pcpu_freelist_push\n    pcpu_freelist_push\n    free_htab_elem\n    htab_map_delete_elem\n    [raw_tp/sys_enter BPF program]\n    __bpf_trace_sys_enter\n    do_syscall_64\n\nraw_res_spin_lock() detects the same-CPU recursive acquisition and\nreturns -EDEADLK, but the subsequent fallback loop has no candidate head\non a system with one possible CPU.\n\nRestore the extra fallback head that existed before the rqspinlock\nconversion. Keep the current-CPU fast path, then try the other possible\nCPUs and finally the extra head. The additional head lets a push, which\ncannot fail without losing a preallocated element, make progress when the\nonly per-CPU head is held by the interrupted context.\n\nAlso check the extra head from the pop path so that nodes placed there\ncan be reused."
    }
  ],
  "id": "CVE-2026-89991",
  "lastModified": "2026-09-16T11:17:10.240",
  "metrics": {},
  "published": "2026-09-16T11:17:10.240",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a24a146ae2cb5d9faeea96d10010fcb6579abe1f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a5b5e62baceff9e252c6535cf42a027d04f226cf"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/efebf6496685c93150df5bb0794363ae70c5f58a"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-89991 (GCVE-0-2026-89991)

Vulnerability from cvelistv5 – Published: 2026-09-16 10:33 – Updated: 2026-09-16 10:33

Title

bpf: Fix infinite loop in pcpu_freelist push with one possible CPU

Summary

Severity

No CVSS data available.

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/a24a146ae2cb5d9fa…
https://git.kernel.org/stable/c/a5b5e62baceff9e25…
https://git.kernel.org/stable/c/efebf6496685c9315…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb , < a24a146ae2cb5d9faeea96d10010fcb6579abe1f (git) Affected: f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb , < a5b5e62baceff9e252c6535cf42a027d04f226cf (git) Affected: f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb , < efebf6496685c93150df5bb0794363ae70c5f58a (git)
Linux	Linux	Affected: 6.15 Unaffected: 0 , < 6.15 (semver) Unaffected: 6.18.51 , ≤ 6.18.* (semver) Unaffected: 7.2.5 , ≤ 7.2.* (semver) Unaffected: 7.3-rc2 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/percpu_freelist.c",
            "kernel/bpf/percpu_freelist.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a24a146ae2cb5d9faeea96d10010fcb6579abe1f",
              "status": "affected",
              "version": "f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb",
              "versionType": "git"
            },
            {
              "lessThan": "a5b5e62baceff9e252c6535cf42a027d04f226cf",
              "status": "affected",
              "version": "f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb",
              "versionType": "git"
            },
            {
              "lessThan": "efebf6496685c93150df5bb0794363ae70c5f58a",
              "status": "affected",
              "version": "f2ac0e5d1c4dcc55d6510dcaefb8f45661a9a1fb",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/percpu_freelist.c",
            "kernel/bpf/percpu_freelist.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.51",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.5",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3-rc2",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix infinite loop in pcpu_freelist push with one possible CPU\n\n__pcpu_freelist_push() can loop forever when only one CPU is possible\nand an NMI re-enters pcpu_freelist_push() while the interrupted context\nholds that CPU\u0027s freelist lock.\n\nAfter the current-CPU fast path fails, the fallback loop walks\ncpu_possible_mask while skipping the current CPU. With CONFIG_SMP=n, or\nwhen an SMP kernel is limited to one possible CPU with nr_cpus=1 or\npossible_cpus=1, there are no other possible CPUs to examine. The loop\ntherefore makes no lock acquisition attempt and can never make progress.\n\nThe following stack was observed on a UP system:\n\n  NMI context:\n    pcpu_freelist_push\n    free_htab_elem\n    htab_map_delete_elem\n    [perf-event BPF program]\n    __perf_event_overflow\n    perf_event_nmi_handler\n    exc_nmi\n\n  Interrupted context:\n    __pcpu_freelist_push\n    pcpu_freelist_push\n    free_htab_elem\n    htab_map_delete_elem\n    [raw_tp/sys_enter BPF program]\n    __bpf_trace_sys_enter\n    do_syscall_64\n\nraw_res_spin_lock() detects the same-CPU recursive acquisition and\nreturns -EDEADLK, but the subsequent fallback loop has no candidate head\non a system with one possible CPU.\n\nRestore the extra fallback head that existed before the rqspinlock\nconversion. Keep the current-CPU fast path, then try the other possible\nCPUs and finally the extra head. The additional head lets a push, which\ncannot fail without losing a preallocated element, make progress when the\nonly per-CPU head is held by the interrupted context.\n\nAlso check the extra head from the pop path so that nodes placed there\ncan be reused."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-16T10:33:05.097Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a24a146ae2cb5d9faeea96d10010fcb6579abe1f"
        },
        {
          "url": "https://git.kernel.org/stable/c/a5b5e62baceff9e252c6535cf42a027d04f226cf"
        },
        {
          "url": "https://git.kernel.org/stable/c/efebf6496685c93150df5bb0794363ae70c5f58a"
        }
      ],
      "title": "bpf: Fix infinite loop in pcpu_freelist push with one possible CPU",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89991",
    "datePublished": "2026-09-16T10:33:05.097Z",
    "dateReserved": "2026-09-11T19:38:34.780Z",
    "dateUpdated": "2026-09-16T10:33:05.097Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Detection rules are retrieved from Rulezet.

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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