linux-cve-announce - CVE-2023-53824: netlink: annotate lockless accesses to nlk->max_recvmsg

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Message-ID: <2025120951-CVE-2023-53824-229c@gregkh>
Date: Tue,  9 Dec 2025 10:31:08 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53824: netlink: annotate lockless accesses to nlk->max_recvmsg_len

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

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

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

netlink: annotate lockless accesses to nlk->max_recvmsg_len

syzbot reported a data-race in data-race in netlink_recvmsg() [1]

Indeed, netlink_recvmsg() can be run concurrently,
and netlink_dump() also needs protection.

[1]
BUG: KCSAN: data-race in netlink_recvmsg / netlink_recvmsg

read to 0xffff888141840b38 of 8 bytes by task 23057 on cpu 0:
netlink_recvmsg+0xea/0x730 net/netlink/af_netlink.c:1988
sock_recvmsg_nosec net/socket.c:1017 [inline]
sock_recvmsg net/socket.c:1038 [inline]
__sys_recvfrom+0x1ee/0x2e0 net/socket.c:2194
__do_sys_recvfrom net/socket.c:2212 [inline]
__se_sys_recvfrom net/socket.c:2208 [inline]
__x64_sys_recvfrom+0x78/0x90 net/socket.c:2208
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff888141840b38 of 8 bytes by task 23037 on cpu 1:
netlink_recvmsg+0x114/0x730 net/netlink/af_netlink.c:1989
sock_recvmsg_nosec net/socket.c:1017 [inline]
sock_recvmsg net/socket.c:1038 [inline]
____sys_recvmsg+0x156/0x310 net/socket.c:2720
___sys_recvmsg net/socket.c:2762 [inline]
do_recvmmsg+0x2e5/0x710 net/socket.c:2856
__sys_recvmmsg net/socket.c:2935 [inline]
__do_sys_recvmmsg net/socket.c:2958 [inline]
__se_sys_recvmmsg net/socket.c:2951 [inline]
__x64_sys_recvmmsg+0xe2/0x160 net/socket.c:2951
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000000 -> 0x0000000000001000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 23037 Comm: syz-executor.2 Not tainted 6.3.0-rc4-syzkaller-00195-g5a57b48fdfcb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023

The Linux kernel CVE team has assigned CVE-2023-53824 to this issue.


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

	Issue introduced in 3.15 with commit 9063e21fb026c4966fc93261c18322214f9835eb and fixed in 5.10.218 with commit 05c9e3fc93b02d18c3ab258d43350a6d44b40bbd
	Issue introduced in 3.15 with commit 9063e21fb026c4966fc93261c18322214f9835eb and fixed in 5.15.160 with commit 7cff4103be7c402ecc3e7bf8f95a64089e3c91b8
	Issue introduced in 3.15 with commit 9063e21fb026c4966fc93261c18322214f9835eb and fixed in 6.1.24 with commit e3bcf2a77060bea4d8d09cb09d92c7056f07df5a
	Issue introduced in 3.15 with commit 9063e21fb026c4966fc93261c18322214f9835eb and fixed in 6.2.11 with commit fc4ba13013ddaea8b11b88fd52b35449e2d9cf85
	Issue introduced in 3.15 with commit 9063e21fb026c4966fc93261c18322214f9835eb and fixed in 6.3 with commit a1865f2e7d10dde00d35a2122b38d2e469ae67ed

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-2023-53824
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/netlink/af_netlink.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/05c9e3fc93b02d18c3ab258d43350a6d44b40bbd
	https://git.kernel.org/stable/c/7cff4103be7c402ecc3e7bf8f95a64089e3c91b8
	https://git.kernel.org/stable/c/e3bcf2a77060bea4d8d09cb09d92c7056f07df5a
	https://git.kernel.org/stable/c/fc4ba13013ddaea8b11b88fd52b35449e2d9cf85
	https://git.kernel.org/stable/c/a1865f2e7d10dde00d35a2122b38d2e469ae67ed