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GHSA-PRW3-7248-3734

Vulnerability from github – Published: 2026-10-18 18:31 – Updated: 2026-10-18 18:31

Details

In the Linux kernel, the following vulnerability has been resolved:

net: flush skb_defer_nodes in dev_cpu_dead()

When a CPU goes offline, dev_cpu_dead() drains its softnet queues (completion_queue, output_queue, poll_list, process_queue, and input_pkt_queue), but leaves net_hotdata.skb_defer_nodes untouched.

If oldcpu goes offline while holding pending skbs in its skb_defer_nodes lists (e.g. below the sysctl_skb_defer_max >> 1 IPI threshold, or if the IPI races with CPU teardown), those skbs remain stranded until oldcpu is brought back online. If any of these skbs hold page_pool fragments, page_pool_destroy() will stall indefinitely waiting for inflight pages to be returned when a netdev or driver is torn down while oldcpu is offline.

Additionally, if smp_call_function_single_async() fails in kick_defer_list_purge() because the target CPU went offline, reset defer_ipi_scheduled to 0 so future IPI kicks are not blocked when the CPU comes back online.

Also, if oldcpu was the last online CPU on its NUMA node, drain that node's slot across all CPUs so no skbs deferred from that node remain stranded on idle remote CPUs (or if the node itself is subsequently offlined).

Finally, in skb_attempt_defer_free(), re-check cpu_online(cpu) and whether the caller migrated CPUs after llist_add(), flushing the node list if so, to close the preemption TOCTOU race against CPU/node teardown.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98558"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-18T16:17:07Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: flush skb_defer_nodes in dev_cpu_dead()\n\nWhen a CPU goes offline, dev_cpu_dead() drains its softnet queues\n(completion_queue, output_queue, poll_list, process_queue, and\ninput_pkt_queue), but leaves net_hotdata.skb_defer_nodes untouched.\n\nIf oldcpu goes offline while holding pending skbs in its\nskb_defer_nodes lists (e.g. below the sysctl_skb_defer_max \u003e\u003e 1 IPI\nthreshold, or if the IPI races with CPU teardown), those skbs remain\nstranded until oldcpu is brought back online. If any of these skbs\nhold page_pool fragments, page_pool_destroy() will stall indefinitely\nwaiting for inflight pages to be returned when a netdev or driver is\ntorn down while oldcpu is offline.\n\nAdditionally, if smp_call_function_single_async() fails in\nkick_defer_list_purge() because the target CPU went offline, reset\ndefer_ipi_scheduled to 0 so future IPI kicks are not blocked when the\nCPU comes back online.\n\nAlso, if oldcpu was the last online CPU on its NUMA node, drain that\nnode\u0027s slot across all CPUs so no skbs deferred from that node remain\nstranded on idle remote CPUs (or if the node itself is subsequently\nofflined).\n\nFinally, in skb_attempt_defer_free(), re-check cpu_online(cpu) and\nwhether the caller migrated CPUs after llist_add(), flushing the node\nlist if so, to close the preemption TOCTOU race against CPU/node\nteardown.",
  "id": "GHSA-prw3-7248-3734",
  "modified": "2026-10-18T18:31:54Z",
  "published": "2026-10-18T18:31:54Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98558"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/06e3f54e8b22040ada01a28343badf1990b4dd7d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c68f4157463448a76893223e117170be8374d773"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-98558 (GCVE-0-2026-98558)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:18 – Updated: 2026-10-19 09:21

Title

net: flush skb_defer_nodes in dev_cpu_dead()

Summary

In the Linux kernel, the following vulnerability has been resolved: net: flush skb_defer_nodes in dev_cpu_dead() When a CPU goes offline, dev_cpu_dead() drains its softnet queues (completion_queue, output_queue, poll_list, process_queue, and input_pkt_queue), but leaves net_hotdata.skb_defer_nodes untouched. If oldcpu goes offline while holding pending skbs in its skb_defer_nodes lists (e.g. below the sysctl_skb_defer_max >> 1 IPI threshold, or if the IPI races with CPU teardown), those skbs remain stranded until oldcpu is brought back online. If any of these skbs hold page_pool fragments, page_pool_destroy() will stall indefinitely waiting for inflight pages to be returned when a netdev or driver is torn down while oldcpu is offline. Additionally, if smp_call_function_single_async() fails in kick_defer_list_purge() because the target CPU went offline, reset defer_ipi_scheduled to 0 so future IPI kicks are not blocked when the CPU comes back online. Also, if oldcpu was the last online CPU on its NUMA node, drain that node's slot across all CPUs so no skbs deferred from that node remain stranded on idle remote CPUs (or if the node itself is subsequently offlined). Finally, in skb_attempt_defer_free(), re-check cpu_online(cpu) and whether the caller migrated CPUs after llist_add(), flushing the node list if so, to close the preemption TOCTOU race against CPU/node teardown.

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6820 records in the last 180 days details

References

2 references

URL	Tags
https://git.kernel.org/stable/c/c68f4157463448a76…
https://git.kernel.org/stable/c/06e3f54e8b22040ad…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 68822bdf76f10c3dc80609d4e2cdc1e847429086 , < c68f4157463448a76893223e117170be8374d773 (git) Affected: 68822bdf76f10c3dc80609d4e2cdc1e847429086 , < 06e3f54e8b22040ada01a28343badf1990b4dd7d (git)
Linux	Linux	Affected: 5.19 Unaffected: 0 , < 5.19 (semver) Unaffected: 7.2.9 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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{
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    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
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          "programFiles": [
            "net/core/dev.c",
            "net/core/dev.h",
            "net/core/skbuff.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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          "versions": [
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              "versionType": "git"
            },
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              "status": "affected",
              "version": "68822bdf76f10c3dc80609d4e2cdc1e847429086",
              "versionType": "git"
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              "version": "0",
              "versionType": "semver"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: flush skb_defer_nodes in dev_cpu_dead()\n\nWhen a CPU goes offline, dev_cpu_dead() drains its softnet queues\n(completion_queue, output_queue, poll_list, process_queue, and\ninput_pkt_queue), but leaves net_hotdata.skb_defer_nodes untouched.\n\nIf oldcpu goes offline while holding pending skbs in its\nskb_defer_nodes lists (e.g. below the sysctl_skb_defer_max \u003e\u003e 1 IPI\nthreshold, or if the IPI races with CPU teardown), those skbs remain\nstranded until oldcpu is brought back online. If any of these skbs\nhold page_pool fragments, page_pool_destroy() will stall indefinitely\nwaiting for inflight pages to be returned when a netdev or driver is\ntorn down while oldcpu is offline.\n\nAdditionally, if smp_call_function_single_async() fails in\nkick_defer_list_purge() because the target CPU went offline, reset\ndefer_ipi_scheduled to 0 so future IPI kicks are not blocked when the\nCPU comes back online.\n\nAlso, if oldcpu was the last online CPU on its NUMA node, drain that\nnode\u0027s slot across all CPUs so no skbs deferred from that node remain\nstranded on idle remote CPUs (or if the node itself is subsequently\nofflined).\n\nFinally, in skb_attempt_defer_free(), re-check cpu_online(cpu) and\nwhether the caller migrated CPUs after llist_add(), flushing the node\nlist if so, to close the preemption TOCTOU race against CPU/node\nteardown."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:21:42.443Z",
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  "cveMetadata": {
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    "datePublished": "2026-10-18T15:18:25.282Z",
    "dateReserved": "2026-09-25T10:25:14.357Z",
    "dateUpdated": "2026-10-19T09:21:42.443Z",
    "state": "PUBLISHED"
  },
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}

Sightings

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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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