linux-cve-announce - CVE-2023-54200: netfilter: nf_tables: always release netdev hooks from notifier

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Message-ID: <2025123030-CVE-2023-54200-8bbb@gregkh>
Date: Tue, 30 Dec 2025 13:10:08 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-54200: netfilter: nf_tables: always release netdev hooks from notifier

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

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

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

netfilter: nf_tables: always release netdev hooks from notifier

This reverts "netfilter: nf_tables: skip netdev events generated on netns removal".

The problem is that when a veth device is released, the veth release
callback will also queue the peer netns device for removal.

Its possible that the peer netns is also slated for removal.  In this
case, the device memory is already released before the pre_exit hook of
the peer netns runs:

BUG: KASAN: slab-use-after-free in nf_hook_entry_head+0x1b8/0x1d0
Read of size 8 at addr ffff88812c0124f0 by task kworker/u8:1/45
Workqueue: netns cleanup_net
Call Trace:
 nf_hook_entry_head+0x1b8/0x1d0
 __nf_unregister_net_hook+0x76/0x510
 nft_netdev_unregister_hooks+0xa0/0x220
 __nft_release_hook+0x184/0x490
 nf_tables_pre_exit_net+0x12f/0x1b0
 ..

Order is:
1. First netns is released, veth_dellink() queues peer netns device
   for removal
2. peer netns is queued for removal
3. peer netns device is released, unreg event is triggered
4. unreg event is ignored because netns is going down
5. pre_exit hook calls nft_netdev_unregister_hooks but device memory
   might be free'd already.

The Linux kernel CVE team has assigned CVE-2023-54200 to this issue.

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

	Issue introduced in 5.15 with commit 68a3765c659f809dcaac20030853a054646eb739 and fixed in 5.15.113 with commit 8d56f00c61f67b450fbbdcb874855e60ad92c560
	Issue introduced in 5.15 with commit 68a3765c659f809dcaac20030853a054646eb739 and fixed in 6.1.30 with commit 30e4b13b1bfbdf3bf3b27036d8209ea1b9f0d880
	Issue introduced in 5.15 with commit 68a3765c659f809dcaac20030853a054646eb739 and fixed in 6.3.4 with commit 94032527efbac13be702c76afb9d872c0cca7a43
	Issue introduced in 5.15 with commit 68a3765c659f809dcaac20030853a054646eb739 and fixed in 6.4 with commit dc1c9fd4a8bbe1e06add9053010b652449bfe411
	Issue introduced in 5.14.15 with commit 90c7c58aa2bd02c65a4c63b7dfe0b16eab12cf9f

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-2023-54200
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:
	net/netfilter/nft_chain_filter.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/8d56f00c61f67b450fbbdcb874855e60ad92c560
	https://git.kernel.org/stable/c/30e4b13b1bfbdf3bf3b27036d8209ea1b9f0d880
	https://git.kernel.org/stable/c/94032527efbac13be702c76afb9d872c0cca7a43
	https://git.kernel.org/stable/c/dc1c9fd4a8bbe1e06add9053010b652449bfe411