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CVE-2023-54149 (GCVE-0-2023-54149)

Vulnerability from cvelistv5 – Published: 2025-12-24 13:07 – Updated: 2026-08-05 09:17
VLAI
Title
net: dsa: avoid suspicious RCU usage for synced VLAN-aware MAC addresses
Summary
In the Linux kernel, the following vulnerability has been resolved: net: dsa: avoid suspicious RCU usage for synced VLAN-aware MAC addresses When using the felix driver (the only one which supports UC filtering and MC filtering) as a DSA master for a random other DSA switch, one can see the following stack trace when the downstream switch ports join a VLAN-aware bridge: ============================= WARNING: suspicious RCU usage ----------------------------- net/8021q/vlan_core.c:238 suspicious rcu_dereference_protected() usage! stack backtrace: Workqueue: dsa_ordered dsa_slave_switchdev_event_work Call trace: lockdep_rcu_suspicious+0x170/0x210 vlan_for_each+0x8c/0x188 dsa_slave_sync_uc+0x128/0x178 __hw_addr_sync_dev+0x138/0x158 dsa_slave_set_rx_mode+0x58/0x70 __dev_set_rx_mode+0x88/0xa8 dev_uc_add+0x74/0xa0 dsa_port_bridge_host_fdb_add+0xec/0x180 dsa_slave_switchdev_event_work+0x7c/0x1c8 process_one_work+0x290/0x568 What it's saying is that vlan_for_each() expects rtnl_lock() context and it's not getting it, when it's called from the DSA master's ndo_set_rx_mode(). The caller of that - dsa_slave_set_rx_mode() - is the slave DSA interface's dsa_port_bridge_host_fdb_add() which comes from the deferred dsa_slave_switchdev_event_work(). We went to great lengths to avoid the rtnl_lock() context in that call path in commit 0faf890fc519 ("net: dsa: drop rtnl_lock from dsa_slave_switchdev_event_work"), and calling rtnl_lock() is simply not an option due to the possibility of deadlocking when calling dsa_flush_workqueue() from the call paths that do hold rtnl_lock() - basically all of them. So, when the DSA master calls vlan_for_each() from its ndo_set_rx_mode(), the state of the 8021q driver on this device is really not protected from concurrent access by anything. Looking at net/8021q/, I don't think that vlan_info->vid_list was particularly designed with RCU traversal in mind, so introducing an RCU read-side form of vlan_for_each() - vlan_for_each_rcu() - won't be so easy, and it also wouldn't be exactly what we need anyway. In general I believe that the solution isn't in net/8021q/ anyway; vlan_for_each() is not cut out for this task. DSA doesn't need rtnl_lock() to be held per se - since it's not a netdev state change that we're blocking, but rather, just concurrent additions/removals to a VLAN list. We don't even need sleepable context - the callback of vlan_for_each() just schedules deferred work. The proposed escape is to remove the dependency on vlan_for_each() and to open-code a non-sleepable, rtnl-free alternative to that, based on copies of the VLAN list modified from .ndo_vlan_rx_add_vid() and .ndo_vlan_rx_kill_vid().
Severity
7.5 (High)
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 64fdc5f341db01200e33105265d4b8450122a82e , < 3948c69b3837fec2ee5a90fbc911c343199be0ac (git)
Affected: 64fdc5f341db01200e33105265d4b8450122a82e , < 3f9e79f31e51b7d5bf95c617540deb6cf2816a3f (git)
Affected: 64fdc5f341db01200e33105265d4b8450122a82e , < d06f925f13976ab82167c93467c70a337a0a3cda (git)
Affected: 2daf967a24334865e51520e55190a646dd480cd7 (git)
Affected: 6.2.10 , < 6.3 (semver)
guessed Create a notification for this product.
Linux Linux Affected: 6.3
Unaffected: 0 , < 6.3 (semver)
Unaffected: 6.3.13 , ≤ 6.3.* (semver)
Unaffected: 6.4.4 , ≤ 6.4.* (semver)
Unaffected: 6.5 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
  "containers": {
    "cna": {
      "affected": [
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
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            "net/dsa/dsa.c",
            "net/dsa/slave.c",
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            "net/dsa/switch.h"
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            "net/dsa/dsa.c",
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            "net/dsa/switch.c",
            "net/dsa/switch.h"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: dsa: avoid suspicious RCU usage for synced VLAN-aware MAC addresses\n\nWhen using the felix driver (the only one which supports UC filtering\nand MC filtering) as a DSA master for a random other DSA switch, one can\nsee the following stack trace when the downstream switch ports join a\nVLAN-aware bridge:\n\n=============================\nWARNING: suspicious RCU usage\n-----------------------------\nnet/8021q/vlan_core.c:238 suspicious rcu_dereference_protected() usage!\n\nstack backtrace:\nWorkqueue: dsa_ordered dsa_slave_switchdev_event_work\nCall trace:\n lockdep_rcu_suspicious+0x170/0x210\n vlan_for_each+0x8c/0x188\n dsa_slave_sync_uc+0x128/0x178\n __hw_addr_sync_dev+0x138/0x158\n dsa_slave_set_rx_mode+0x58/0x70\n __dev_set_rx_mode+0x88/0xa8\n dev_uc_add+0x74/0xa0\n dsa_port_bridge_host_fdb_add+0xec/0x180\n dsa_slave_switchdev_event_work+0x7c/0x1c8\n process_one_work+0x290/0x568\n\nWhat it\u0027s saying is that vlan_for_each() expects rtnl_lock() context and\nit\u0027s not getting it, when it\u0027s called from the DSA master\u0027s ndo_set_rx_mode().\n\nThe caller of that - dsa_slave_set_rx_mode() - is the slave DSA\ninterface\u0027s dsa_port_bridge_host_fdb_add() which comes from the deferred\ndsa_slave_switchdev_event_work().\n\nWe went to great lengths to avoid the rtnl_lock() context in that call\npath in commit 0faf890fc519 (\"net: dsa: drop rtnl_lock from\ndsa_slave_switchdev_event_work\"), and calling rtnl_lock() is simply not\nan option due to the possibility of deadlocking when calling\ndsa_flush_workqueue() from the call paths that do hold rtnl_lock() -\nbasically all of them.\n\nSo, when the DSA master calls vlan_for_each() from its ndo_set_rx_mode(),\nthe state of the 8021q driver on this device is really not protected\nfrom concurrent access by anything.\n\nLooking at net/8021q/, I don\u0027t think that vlan_info-\u003evid_list was\nparticularly designed with RCU traversal in mind, so introducing an RCU\nread-side form of vlan_for_each() - vlan_for_each_rcu() - won\u0027t be so\neasy, and it also wouldn\u0027t be exactly what we need anyway.\n\nIn general I believe that the solution isn\u0027t in net/8021q/ anyway;\nvlan_for_each() is not cut out for this task. DSA doesn\u0027t need rtnl_lock()\nto be held per se - since it\u0027s not a netdev state change that we\u0027re\nblocking, but rather, just concurrent additions/removals to a VLAN list.\nWe don\u0027t even need sleepable context - the callback of vlan_for_each()\njust schedules deferred work.\n\nThe proposed escape is to remove the dependency on vlan_for_each() and\nto open-code a non-sleepable, rtnl-free alternative to that, based on\ncopies of the VLAN list modified from .ndo_vlan_rx_add_vid() and\n.ndo_vlan_rx_kill_vid()."
        }
      ],
      "metrics": [
        {
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            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - The unlocked `vlan_for_each()` traversal is reached from the DSA deferred FDB workqueue, which is fed by bridge FDB learning of source MACs from received Ethernet frames (assisted_learning_on_cpu_port is set by felix/sja1105/mt7530, and foreign-port entries become host addresses). Driving that learning requires being on the same layer-2 segment as the switch appliance, so the reach is adjacent, not routed-network.\nAC:H - The attacker can execute the unsynchronized `vid_list` walk at arbitrary rate via MAC flooding, but the freeing side (`__vlan_vid_del()` from `dsa_port_host_vlan_add/del`) only runs during rtnl-held VLAN reconfiguration, which is outside the attacker\u0027s control. Winning the use-after-free therefore depends on a condition the attacker cannot induce.\nPR:N - No credentials or account on the target are needed \u2014 the vulnerable path is entered purely by the bridge learning attacker-supplied source MAC addresses off the wire and offloading them as host FDB entries. The attacker never issues a syscall on the device.\nUI:N - The FDB learning, switchdev notification and deferred work all occur automatically on frame reception; no operator action is required once the device is in its normal bridged/VLAN-aware configuration.\nS:U - The corrupted state (`vlan_info-\u003evid_list`) and the resulting fault are both inside the kernel, the same security authority that is compromised. No hypervisor, IOMMU or sandbox boundary is crossed.\nC:H - Traversing a `list_del`\u0027d-and-`kfree`\u0027d `vlan_vid_info` is a use-after-free read: the stale `list.next` sends the walk into reallocated or arbitrary kernel memory, and the harvested `vid`/`proto` values are programmed as host FDB/MDB filters, which can also punt traffic from VLANs the host was isolated from. Per UAF guidance this is High.\nI:H - The use-after-free lets reallocated heap contents dictate control flow of the list walk and the VLAN IDs written into the switch\u0027s hardware forwarding tables, corrupting VLAN isolation; UAFs of this class are treated as High integrity impact since heap grooming turns them into corruption primitives.\nA:H - Even absent the race the path unconditionally fires `ASSERT_RTNL()`\u0027s `WARN_ONCE` (a panic under panic_on_warn) plus a lockdep RCU splat, and dereferencing a freed or LIST_POISON\u0027d `next` pointer oopses the kernel in workqueue context, taking down the switch appliance."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T09:17:38.014Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/3948c69b3837fec2ee5a90fbc911c343199be0ac"
        },
        {
          "url": "https://git.kernel.org/stable/c/3f9e79f31e51b7d5bf95c617540deb6cf2816a3f"
        },
        {
          "url": "https://git.kernel.org/stable/c/d06f925f13976ab82167c93467c70a337a0a3cda"
        }
      ],
      "title": "net: dsa: avoid suspicious RCU usage for synced VLAN-aware MAC addresses",
      "x_generator": {
        "engine": "bippy-1.2.0"
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2023-54149",
    "datePublished": "2025-12-24T13:07:00.977Z",
    "dateReserved": "2025-12-24T13:02:52.528Z",
    "dateUpdated": "2026-08-05T09:17:38.014Z",
    "state": "PUBLISHED"
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  "dataVersion": "5.2",
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      "date": "2026-09-20",
      "epss": "0.0025",
      "percentile": "0.16687"
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                "vendor": "Linux",
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              }
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: dsa: avoid suspicious RCU usage for synced VLAN-aware MAC addresses\n\nWhen using the felix driver (the only one which supports UC filtering\nand MC filtering) as a DSA master for a random other DSA switch, one can\nsee the following stack trace when the downstream switch ports join a\nVLAN-aware bridge:\n\n=============================\nWARNING: suspicious RCU usage\n-----------------------------\nnet/8021q/vlan_core.c:238 suspicious rcu_dereference_protected() usage!\n\nstack backtrace:\nWorkqueue: dsa_ordered dsa_slave_switchdev_event_work\nCall trace:\n lockdep_rcu_suspicious+0x170/0x210\n vlan_for_each+0x8c/0x188\n dsa_slave_sync_uc+0x128/0x178\n __hw_addr_sync_dev+0x138/0x158\n dsa_slave_set_rx_mode+0x58/0x70\n __dev_set_rx_mode+0x88/0xa8\n dev_uc_add+0x74/0xa0\n dsa_port_bridge_host_fdb_add+0xec/0x180\n dsa_slave_switchdev_event_work+0x7c/0x1c8\n process_one_work+0x290/0x568\n\nWhat it\u0027s saying is that vlan_for_each() expects rtnl_lock() context and\nit\u0027s not getting it, when it\u0027s called from the DSA master\u0027s ndo_set_rx_mode().\n\nThe caller of that - dsa_slave_set_rx_mode() - is the slave DSA\ninterface\u0027s dsa_port_bridge_host_fdb_add() which comes from the deferred\ndsa_slave_switchdev_event_work().\n\nWe went to great lengths to avoid the rtnl_lock() context in that call\npath in commit 0faf890fc519 (\"net: dsa: drop rtnl_lock from\ndsa_slave_switchdev_event_work\"), and calling rtnl_lock() is simply not\nan option due to the possibility of deadlocking when calling\ndsa_flush_workqueue() from the call paths that do hold rtnl_lock() -\nbasically all of them.\n\nSo, when the DSA master calls vlan_for_each() from its ndo_set_rx_mode(),\nthe state of the 8021q driver on this device is really not protected\nfrom concurrent access by anything.\n\nLooking at net/8021q/, I don\u0027t think that vlan_info-\u003evid_list was\nparticularly designed with RCU traversal in mind, so introducing an RCU\nread-side form of vlan_for_each() - vlan_for_each_rcu() - won\u0027t be so\neasy, and it also wouldn\u0027t be exactly what we need anyway.\n\nIn general I believe that the solution isn\u0027t in net/8021q/ anyway;\nvlan_for_each() is not cut out for this task. DSA doesn\u0027t need rtnl_lock()\nto be held per se - since it\u0027s not a netdev state change that we\u0027re\nblocking, but rather, just concurrent additions/removals to a VLAN list.\nWe don\u0027t even need sleepable context - the callback of vlan_for_each()\njust schedules deferred work.\n\nThe proposed escape is to remove the dependency on vlan_for_each() and\nto open-code a non-sleepable, rtnl-free alternative to that, based on\ncopies of the VLAN list modified from .ndo_vlan_rx_add_vid() and\n.ndo_vlan_rx_kill_vid()."
          }
        ],
        "id": "CVE-2023-54149",
        "lastModified": "2026-08-04T11:16:33.170",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "HIGH",
                "attackVector": "ADJACENT_NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 7.5,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.6,
              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
          ]
        },
        "published": "2025-12-24T13:16:16.910",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/3948c69b3837fec2ee5a90fbc911c343199be0ac"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/3f9e79f31e51b7d5bf95c617540deb6cf2816a3f"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/d06f925f13976ab82167c93467c70a337a0a3cda"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Deferred"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-08-04T22:52:48+00:00",
      "cve": "CVE-2023-54149",
      "id": "CVE-2023-54149",
      "initial_release_date": "2023-01-01T00:00:00+00:00",
      "product_status:known_affected": "14",
      "product_status:known_not_affected": "260",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net: dsa: avoid suspicious RCU usage for synced VLAN-aware MAC addresses",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-54149.json",
      "version": "3"
    }
  }
}



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  • 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.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.