{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2023-54149","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-12-24T13:02:52.528Z","datePublished":"2025-12-24T13:07:00.977Z","dateUpdated":"2026-08-05T09:17:38.014Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T09:17:38.014Z"},"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()."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"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's 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 — 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->vid_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`'d-and-`kfree`'d `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's 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()`'s `WARN_ONCE` (a panic under panic_on_warn) plus a lockdep RCU splat, and dereferencing a freed or LIST_POISON'd `next` pointer oopses the kernel in workqueue context, taking down the switch appliance."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/dsa.h","net/dsa/dsa.c","net/dsa/slave.c","net/dsa/switch.c","net/dsa/switch.h"],"versions":[{"version":"64fdc5f341db01200e33105265d4b8450122a82e","lessThan":"3948c69b3837fec2ee5a90fbc911c343199be0ac","status":"affected","versionType":"git"},{"version":"64fdc5f341db01200e33105265d4b8450122a82e","lessThan":"3f9e79f31e51b7d5bf95c617540deb6cf2816a3f","status":"affected","versionType":"git"},{"version":"64fdc5f341db01200e33105265d4b8450122a82e","lessThan":"d06f925f13976ab82167c93467c70a337a0a3cda","status":"affected","versionType":"git"},{"version":"2daf967a24334865e51520e55190a646dd480cd7","status":"affected","versionType":"git"},{"version":"6.2.10","lessThan":"6.3","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/dsa.h","net/dsa/dsa.c","net/dsa/slave.c","net/dsa/switch.c","net/dsa/switch.h"],"versions":[{"version":"6.3","status":"affected"},{"version":"0","lessThan":"6.3","status":"unaffected","versionType":"semver"},{"version":"6.3.13","lessThanOrEqual":"6.3.*","status":"unaffected","versionType":"semver"},{"version":"6.4.4","lessThanOrEqual":"6.4.*","status":"unaffected","versionType":"semver"},{"version":"6.5","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.3.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.4.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.2.10"}]}]}],"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":{"engine":"bippy-1.2.0"}}}}