CVE-2026-45845 (GCVE-0-2026-45845)

Vulnerability from cvelistv5 – Published: 2026-05-27 09:24 – Updated: 2026-05-27 09:24
VLAI
Title
net/sched: taprio: fix NULL pointer dereference in class dump
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: taprio: fix NULL pointer dereference in class dump When a TAPRIO child qdisc is deleted via RTM_DELQDISC, taprio_graft() is called with new == NULL and stores NULL into q->qdiscs[cl - 1]. Subsequent RTM_GETTCLASS dump operations walk all classes via taprio_walk() and call taprio_dump_class(), which calls taprio_leaf() returning the NULL pointer, then dereferences it to read child->handle, causing a kernel NULL pointer dereference. The bug is reachable with namespace-scoped CAP_NET_ADMIN on any kernel with CONFIG_NET_SCH_TAPRIO enabled. On systems with unprivileged user namespaces enabled, an unprivileged local user can trigger a kernel panic by creating a taprio qdisc inside a new network namespace, grafting an explicit child qdisc, deleting it, and requesting a class dump. The RTM_GETTCLASS dump itself requires no capability. Oops: general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f] RIP: 0010:taprio_dump_class (net/sched/sch_taprio.c:2478) Call Trace: <TASK> tc_fill_tclass (net/sched/sch_api.c:1966) qdisc_class_dump (net/sched/sch_api.c:2326) taprio_walk (net/sched/sch_taprio.c:2514) tc_dump_tclass_qdisc (net/sched/sch_api.c:2352) tc_dump_tclass_root (net/sched/sch_api.c:2370) tc_dump_tclass (net/sched/sch_api.c:2431) rtnl_dumpit (net/core/rtnetlink.c:6864) netlink_dump (net/netlink/af_netlink.c:2325) rtnetlink_rcv_msg (net/core/rtnetlink.c:6959) netlink_rcv_skb (net/netlink/af_netlink.c:2550) </TASK> Fix this by substituting &noop_qdisc when new is NULL in taprio_graft(), a common pattern used by other qdiscs (e.g., multiq_graft()) to ensure the q->qdiscs[] slots are never NULL. This makes control-plane dump paths safe without requiring individual NULL checks. Since the data-plane paths (taprio_enqueue and taprio_dequeue_from_txq) previously had explicit NULL guards that would drop/skip the packet cleanly, update those checks to test for &noop_qdisc instead. Without this, packets would reach taprio_enqueue_one() which increments the root qdisc's qlen and backlog before calling the child's enqueue; noop_qdisc drops the packet but those counters are never rolled back, permanently inflating the root qdisc's statistics. After this change *old can be a valid qdisc, NULL, or &noop_qdisc. Only call qdisc_put(*old) in the first case to avoid decreasing noop_qdisc's refcount, which was never increased.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 665338b2a7a0139337d1f85be65ed16e487f84c1 , < ec2501e361b08b50bcb1e7b3253fc861abbda28d (git)
Affected: 665338b2a7a0139337d1f85be65ed16e487f84c1 , < d02e2fbf60de46678e2ea698a6a904fd21e1cc31 (git)
Affected: 665338b2a7a0139337d1f85be65ed16e487f84c1 , < 48b26d48e76221dc90b02bf5428bab53643461ca (git)
Affected: 665338b2a7a0139337d1f85be65ed16e487f84c1 , < 8f1ff8866cb9f655e5faea6994eb902960be8e04 (git)
Affected: 665338b2a7a0139337d1f85be65ed16e487f84c1 , < 3d07ca5c0fae311226f737963984bd94bb159a87 (git)
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Linux Linux Affected: 6.6
Unaffected: 0 , < 6.6 (semver)
Unaffected: 6.6.141 , ≤ 6.6.* (semver)
Unaffected: 6.12.91 , ≤ 6.12.* (semver)
Unaffected: 6.18.33 , ≤ 6.18.* (semver)
Unaffected: 7.0.10 , ≤ 7.0.* (semver)
Unaffected: 7.1-rc2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/sch_taprio.c"
          ],
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              "versionType": "git"
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          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "version": "6.18.33",
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              "version": "7.0.10",
              "versionType": "semver"
            },
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              "version": "7.1-rc2",
              "versionType": "original_commit_for_fix"
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        }
      ],
      "cpeApplicability": [
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          "nodes": [
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                  "versionEndExcluding": "6.6.141",
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              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: taprio: fix NULL pointer dereference in class dump\n\nWhen a TAPRIO child qdisc is deleted via RTM_DELQDISC, taprio_graft()\nis called with new == NULL and stores NULL into q-\u003eqdiscs[cl - 1].\nSubsequent RTM_GETTCLASS dump operations walk all classes via\ntaprio_walk() and call taprio_dump_class(), which calls taprio_leaf()\nreturning the NULL pointer, then dereferences it to read child-\u003ehandle,\ncausing a kernel NULL pointer dereference.\n\nThe bug is reachable with namespace-scoped CAP_NET_ADMIN on any kernel\nwith CONFIG_NET_SCH_TAPRIO enabled. On systems with unprivileged user\nnamespaces enabled, an unprivileged local user can trigger a kernel\npanic by creating a taprio qdisc inside a new network namespace,\ngrafting an explicit child qdisc, deleting it, and requesting a class\ndump. The RTM_GETTCLASS dump itself requires no capability.\n\n Oops: general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] SMP KASAN NOPTI\n KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]\n RIP: 0010:taprio_dump_class (net/sched/sch_taprio.c:2478)\n Call Trace:\n  \u003cTASK\u003e\n  tc_fill_tclass (net/sched/sch_api.c:1966)\n  qdisc_class_dump (net/sched/sch_api.c:2326)\n  taprio_walk (net/sched/sch_taprio.c:2514)\n  tc_dump_tclass_qdisc (net/sched/sch_api.c:2352)\n  tc_dump_tclass_root (net/sched/sch_api.c:2370)\n  tc_dump_tclass (net/sched/sch_api.c:2431)\n  rtnl_dumpit (net/core/rtnetlink.c:6864)\n  netlink_dump (net/netlink/af_netlink.c:2325)\n  rtnetlink_rcv_msg (net/core/rtnetlink.c:6959)\n  netlink_rcv_skb (net/netlink/af_netlink.c:2550)\n  \u003c/TASK\u003e\n\nFix this by substituting \u0026noop_qdisc when new is NULL in\ntaprio_graft(), a common pattern used by other qdiscs (e.g.,\nmultiq_graft()) to ensure the q-\u003eqdiscs[] slots are never NULL.\nThis makes control-plane dump paths safe without requiring individual\nNULL checks.\n\nSince the data-plane paths (taprio_enqueue and taprio_dequeue_from_txq)\npreviously had explicit NULL guards that would drop/skip the packet\ncleanly, update those checks to test for \u0026noop_qdisc instead. Without\nthis, packets would reach taprio_enqueue_one() which increments the root\nqdisc\u0027s qlen and backlog before calling the child\u0027s enqueue; noop_qdisc\ndrops the packet but those counters are never rolled back, permanently\ninflating the root qdisc\u0027s statistics.\n\nAfter this change *old can be a valid qdisc, NULL, or \u0026noop_qdisc.\nOnly call qdisc_put(*old) in the first case to avoid decreasing\nnoop_qdisc\u0027s refcount, which was never increased."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-27T09:24:48.438Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ec2501e361b08b50bcb1e7b3253fc861abbda28d"
        },
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          "url": "https://git.kernel.org/stable/c/d02e2fbf60de46678e2ea698a6a904fd21e1cc31"
        },
        {
          "url": "https://git.kernel.org/stable/c/48b26d48e76221dc90b02bf5428bab53643461ca"
        },
        {
          "url": "https://git.kernel.org/stable/c/8f1ff8866cb9f655e5faea6994eb902960be8e04"
        },
        {
          "url": "https://git.kernel.org/stable/c/3d07ca5c0fae311226f737963984bd94bb159a87"
        }
      ],
      "title": "net/sched: taprio: fix NULL pointer dereference in class dump",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-45845",
    "datePublished": "2026-05-27T09:24:48.438Z",
    "dateReserved": "2026-05-13T15:03:33.078Z",
    "dateUpdated": "2026-05-27T09:24:48.438Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-45845",
      "date": "2026-05-28",
      "epss": "0.00018",
      "percentile": "0.05152"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-45845\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-05-27T11:16:23.960\",\"lastModified\":\"2026-05-27T14:48:31.480\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnet/sched: taprio: fix NULL pointer dereference in class dump\\n\\nWhen a TAPRIO child qdisc is deleted via RTM_DELQDISC, taprio_graft()\\nis called with new == NULL and stores NULL into q-\u003eqdiscs[cl - 1].\\nSubsequent RTM_GETTCLASS dump operations walk all classes via\\ntaprio_walk() and call taprio_dump_class(), which calls taprio_leaf()\\nreturning the NULL pointer, then dereferences it to read child-\u003ehandle,\\ncausing a kernel NULL pointer dereference.\\n\\nThe bug is reachable with namespace-scoped CAP_NET_ADMIN on any kernel\\nwith CONFIG_NET_SCH_TAPRIO enabled. On systems with unprivileged user\\nnamespaces enabled, an unprivileged local user can trigger a kernel\\npanic by creating a taprio qdisc inside a new network namespace,\\ngrafting an explicit child qdisc, deleting it, and requesting a class\\ndump. The RTM_GETTCLASS dump itself requires no capability.\\n\\n Oops: general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] SMP KASAN NOPTI\\n KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]\\n RIP: 0010:taprio_dump_class (net/sched/sch_taprio.c:2478)\\n Call Trace:\\n  \u003cTASK\u003e\\n  tc_fill_tclass (net/sched/sch_api.c:1966)\\n  qdisc_class_dump (net/sched/sch_api.c:2326)\\n  taprio_walk (net/sched/sch_taprio.c:2514)\\n  tc_dump_tclass_qdisc (net/sched/sch_api.c:2352)\\n  tc_dump_tclass_root (net/sched/sch_api.c:2370)\\n  tc_dump_tclass (net/sched/sch_api.c:2431)\\n  rtnl_dumpit (net/core/rtnetlink.c:6864)\\n  netlink_dump (net/netlink/af_netlink.c:2325)\\n  rtnetlink_rcv_msg (net/core/rtnetlink.c:6959)\\n  netlink_rcv_skb (net/netlink/af_netlink.c:2550)\\n  \u003c/TASK\u003e\\n\\nFix this by substituting \u0026noop_qdisc when new is NULL in\\ntaprio_graft(), a common pattern used by other qdiscs (e.g.,\\nmultiq_graft()) to ensure the q-\u003eqdiscs[] slots are never NULL.\\nThis makes control-plane dump paths safe without requiring individual\\nNULL checks.\\n\\nSince the data-plane paths (taprio_enqueue and taprio_dequeue_from_txq)\\npreviously had explicit NULL guards that would drop/skip the packet\\ncleanly, update those checks to test for \u0026noop_qdisc instead. Without\\nthis, packets would reach taprio_enqueue_one() which increments the root\\nqdisc\u0027s qlen and backlog before calling the child\u0027s enqueue; noop_qdisc\\ndrops the packet but those counters are never rolled back, permanently\\ninflating the root qdisc\u0027s statistics.\\n\\nAfter this change *old can be a valid qdisc, NULL, or \u0026noop_qdisc.\\nOnly call qdisc_put(*old) in the first case to avoid decreasing\\nnoop_qdisc\u0027s refcount, which was never increased.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/3d07ca5c0fae311226f737963984bd94bb159a87\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/48b26d48e76221dc90b02bf5428bab53643461ca\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/8f1ff8866cb9f655e5faea6994eb902960be8e04\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d02e2fbf60de46678e2ea698a6a904fd21e1cc31\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ec2501e361b08b50bcb1e7b3253fc861abbda28d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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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.
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  • 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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