CVE-2023-54149
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!
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().
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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().
Detalles técnicos trazas, registros y código del informe original
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
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 7.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.25%
- Percentil entre todas las CVEs puntuadas: 15
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1210Exploitation of Remote Serviceslateral movement60 %
Inferido por reglas deterministas a partir del vector CVSS y la CWE. Solo orientativo.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
Mostrar
{
"id": "CVE-2023-54149",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Secondary",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 7.5,
"attackVector": "ADJACENT_NETWORK",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "HIGH",
"availabilityImpact": "HIGH",
"privilegesRequired": "NONE",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"exploitabilityScore": 1.6
}
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"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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{
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{
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{
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"programFiles": [
"include/net/dsa.h",
"net/dsa/dsa.c",
"net/dsa/slave.c",
"net/dsa/switch.c",
"net/dsa/switch.h"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
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{
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{
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"versionType": "semver",
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{
"status": "unaffected",
"version": "6.4.4",
"versionType": "semver",
"lessThanOrEqual": "6.4.*"
},
{
"status": "unaffected",
"version": "6.5",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
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"net/dsa/dsa.c",
"net/dsa/slave.c",
"net/dsa/switch.c",
"net/dsa/switch.h"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2025-12-24T13:16:16.910",
"references": [
{
"url": "https://git.kernel.org/stable/c/3948c69b3837fec2ee5a90fbc911c343199be0ac",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
"url": "https://git.kernel.org/stable/c/d06f925f13976ab82167c93467c70a337a0a3cda",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Deferred",
"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's saying is that vlan_for_each() expects rtnl_lock() context and\nit's not getting it, when it's called from the DSA master's ndo_set_rx_mode().\n\nThe caller of that - dsa_slave_set_rx_mode() - is the slave DSA\ninterface's 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't think that vlan_info->vid_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't be so\neasy, and it also wouldn't be exactly what we need anyway.\n\nIn general I believe that the solution isn't in net/8021q/ anyway;\nvlan_for_each() is not cut out for this task. DSA doesn't need rtnl_lock()\nto be held per se - since it's not a netdev state change that we're\nblocking, but rather, just concurrent additions/removals to a VLAN list.\nWe don't 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()."
}
],
"lastModified": "2026-08-04T11:16:33.170",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}