linux-cve-announce - CVE-2023-53566: netfilter: nft_set_rbtree: fix null deref on element insertion

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Message-ID: <2025100451-CVE-2023-53566-1c57@gregkh>
Date: Sat,  4 Oct 2025 17:17:20 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53566: netfilter: nft_set_rbtree: fix null deref on element insertion

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

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

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

netfilter: nft_set_rbtree: fix null deref on element insertion

There is no guarantee that rb_prev() will not return NULL in nft_rbtree_gc_elem():

general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
 nft_add_set_elem+0x14b0/0x2990
  nf_tables_newsetelem+0x528/0xb30

Furthermore, there is a possible use-after-free while iterating,
'node' can be free'd so we need to cache the next value to use.

The Linux kernel CVE team has assigned CVE-2023-53566 to this issue.


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

	Issue introduced in 5.10.166 with commit 4aacf3d78424293e318c616016865380b37b9cc5 and fixed in 5.10.181 with commit 3fa13203b6d90cc3a33af47b058739f92ab82eef
	Issue introduced in 5.15.91 with commit 2bf1435fa19d2c58054391b3bba40d5510a5758c and fixed in 5.15.113 with commit ec5caa765f7f6960011c919c9aeb1467940421f6
	Issue introduced in 6.1.9 with commit 318cb24a4c3fce8140afaf84e4d45fcb76fb280b and fixed in 6.1.30 with commit a836be60a3aabcedcd9c79f545d409ace1f20ba6
	Issue introduced in 6.2 with commit c9e6978e2725a7d4b6cd23b2facd3f11422c0643 and fixed in 6.3.4 with commit a337706c1fb35aac3f26b48aca80421bdbe1d33a
	Issue introduced in 6.2 with commit c9e6978e2725a7d4b6cd23b2facd3f11422c0643 and fixed in 6.4 with commit 61ae320a29b0540c16931816299eb86bf2b66c08

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-2023-53566
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_set_rbtree.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/b76db53ee8802ee5683f8cb401d7e2ec6f9b3d56
	https://git.kernel.org/stable/c/899aa5638568abf5d69de7a7bb95e4615157375b
	https://git.kernel.org/stable/c/3fa13203b6d90cc3a33af47b058739f92ab82eef
	https://git.kernel.org/stable/c/ec5caa765f7f6960011c919c9aeb1467940421f6
	https://git.kernel.org/stable/c/a836be60a3aabcedcd9c79f545d409ace1f20ba6
	https://git.kernel.org/stable/c/a337706c1fb35aac3f26b48aca80421bdbe1d33a
	https://git.kernel.org/stable/c/61ae320a29b0540c16931816299eb86bf2b66c08