linux-cve-announce - CVE-2023-53855: net: dsa: ocelot: call dsa_tag_8021q_unregister() under rtnl

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Message-ID: <2025120902-CVE-2023-53855-9798@gregkh>
Date: Tue,  9 Dec 2025 10:31:39 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53855: net: dsa: ocelot: call dsa_tag_8021q_unregister() under rtnl_lock() on driver remove

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

net: dsa: ocelot: call dsa_tag_8021q_unregister() under rtnl_lock() on driver remove

When the tagging protocol in current use is "ocelot-8021q" and we unbind
the driver, we see this splat:

$ echo '0000:00:00.2' > /sys/bus/pci/drivers/fsl_enetc/unbind
mscc_felix 0000:00:00.5 swp0: left promiscuous mode
sja1105 spi2.0: Link is Down
DSA: tree 1 torn down
mscc_felix 0000:00:00.5 swp2: left promiscuous mode
sja1105 spi2.2: Link is Down
DSA: tree 3 torn down
fsl_enetc 0000:00:00.2 eno2: left promiscuous mode
mscc_felix 0000:00:00.5: Link is Down
------------[ cut here ]------------
RTNL: assertion failed at net/dsa/tag_8021q.c (409)
WARNING: CPU: 1 PID: 329 at net/dsa/tag_8021q.c:409 dsa_tag_8021q_unregister+0x12c/0x1a0
Modules linked in:
CPU: 1 PID: 329 Comm: bash Not tainted 6.5.0-rc3+ #771
pc : dsa_tag_8021q_unregister+0x12c/0x1a0
lr : dsa_tag_8021q_unregister+0x12c/0x1a0
Call trace:
 dsa_tag_8021q_unregister+0x12c/0x1a0
 felix_tag_8021q_teardown+0x130/0x150
 felix_teardown+0x3c/0xd8
 dsa_tree_teardown_switches+0xbc/0xe0
 dsa_unregister_switch+0x168/0x260
 felix_pci_remove+0x30/0x60
 pci_device_remove+0x4c/0x100
 device_release_driver_internal+0x188/0x288
 device_links_unbind_consumers+0xfc/0x138
 device_release_driver_internal+0xe0/0x288
 device_driver_detach+0x24/0x38
 unbind_store+0xd8/0x108
 drv_attr_store+0x30/0x50
---[ end trace 0000000000000000 ]---
------------[ cut here ]------------
RTNL: assertion failed at net/8021q/vlan_core.c (376)
WARNING: CPU: 1 PID: 329 at net/8021q/vlan_core.c:376 vlan_vid_del+0x1b8/0x1f0
CPU: 1 PID: 329 Comm: bash Tainted: G        W          6.5.0-rc3+ #771
pc : vlan_vid_del+0x1b8/0x1f0
lr : vlan_vid_del+0x1b8/0x1f0
 dsa_tag_8021q_unregister+0x8c/0x1a0
 felix_tag_8021q_teardown+0x130/0x150
 felix_teardown+0x3c/0xd8
 dsa_tree_teardown_switches+0xbc/0xe0
 dsa_unregister_switch+0x168/0x260
 felix_pci_remove+0x30/0x60
 pci_device_remove+0x4c/0x100
 device_release_driver_internal+0x188/0x288
 device_links_unbind_consumers+0xfc/0x138
 device_release_driver_internal+0xe0/0x288
 device_driver_detach+0x24/0x38
 unbind_store+0xd8/0x108
 drv_attr_store+0x30/0x50
DSA: tree 0 torn down

This was somewhat not so easy to spot, because "ocelot-8021q" is not the
default tagging protocol, and thus, not everyone who tests the unbinding
path may have switched to it beforehand. The default
felix_tag_npi_teardown() does not require rtnl_lock() to be held.

The Linux kernel CVE team has assigned CVE-2023-53855 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.12 with commit 7c83a7c539abe9f980996063ac20532a7a7f6eb1 and fixed in 6.1.46 with commit 758dbcfb257e1aee0a310bae789c2af6ffe35d0f
	Issue introduced in 5.12 with commit 7c83a7c539abe9f980996063ac20532a7a7f6eb1 and fixed in 6.4.11 with commit 7ae8fa6b70975b6efbbef7912d09bff5a0bff491
	Issue introduced in 5.12 with commit 7c83a7c539abe9f980996063ac20532a7a7f6eb1 and fixed in 6.5 with commit a94c16a2fda010866b8858a386a8bfbeba4f72c5

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2023-53855
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/net/dsa/ocelot/felix.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/758dbcfb257e1aee0a310bae789c2af6ffe35d0f
	https://git.kernel.org/stable/c/7ae8fa6b70975b6efbbef7912d09bff5a0bff491
	https://git.kernel.org/stable/c/a94c16a2fda010866b8858a386a8bfbeba4f72c5