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

Vulnerability from cvelistv5 – Published: 2025-12-24 13:07 – Updated: 2025-12-24 13:07
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 ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 64fdc5f341db01200e33105265d4b8450122a82e , < 3948c69b3837fec2ee5a90fbc911c343199be0ac (git)
Affected: 64fdc5f341db01200e33105265d4b8450122a82e , < 3f9e79f31e51b7d5bf95c617540deb6cf2816a3f (git)
Affected: 64fdc5f341db01200e33105265d4b8450122a82e , < d06f925f13976ab82167c93467c70a337a0a3cda (git)
Affected: 2daf967a24334865e51520e55190a646dd480cd7 (git)
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    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)
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{
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/dsa.h",
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            "net/dsa/switch.c",
            "net/dsa/switch.h"
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            "net/dsa/slave.c",
            "net/dsa/switch.c",
            "net/dsa/switch.h"
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          "vendor": "Linux",
          "versions": [
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              "version": "6.3"
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            {
              "lessThanOrEqual": "6.3.*",
              "status": "unaffected",
              "version": "6.3.13",
              "versionType": "semver"
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      "cpeApplicability": [
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                  "versionEndExcluding": "6.3.13",
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              "negate": false,
              "operator": "OR"
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      "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()."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-12-24T13:07:00.977Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "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": {
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2023-54149",
    "datePublished": "2025-12-24T13:07:00.977Z",
    "dateReserved": "2025-12-24T13:02:52.528Z",
    "dateUpdated": "2025-12-24T13:07:00.977Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2"
}


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