linux-cve-announce - CVE-2025-38271: net: prevent a NULL deref in rtnl_create

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Message-ID: <2025071008-CVE-2025-38271-5db2@gregkh>
Date: Thu, 10 Jul 2025 09:42:12 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38271: net: prevent a NULL deref in rtnl_create_link()

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

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

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

net: prevent a NULL deref in rtnl_create_link()

At the time rtnl_create_link() is running, dev->netdev_ops is NULL,
we must not use netdev_lock_ops() or risk a NULL deref if
CONFIG_NET_SHAPER is defined.

Use netif_set_group() instead of dev_set_group().

 RIP: 0010:netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]
 RIP: 0010:netdev_lock_ops include/net/netdev_lock.h:41 [inline]
 RIP: 0010:dev_set_group+0xc0/0x230 net/core/dev_api.c:82
Call Trace:
 <TASK>
  rtnl_create_link+0x748/0xd10 net/core/rtnetlink.c:3674
  rtnl_newlink_create+0x25c/0xb00 net/core/rtnetlink.c:3813
  __rtnl_newlink net/core/rtnetlink.c:3940 [inline]
  rtnl_newlink+0x16d6/0x1c70 net/core/rtnetlink.c:4055
  rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6944
  netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
  netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
  netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
  netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
  sock_sendmsg_nosec net/socket.c:712 [inline]

The Linux kernel CVE team has assigned CVE-2025-38271 to this issue.


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

	Issue introduced in 6.15 with commit 7e4d784f5810bba76c4593791028e13cce4af547 and fixed in 6.15.3 with commit 8a29ae8428a5c26f0b4471c2057d9e9415c53109
	Issue introduced in 6.15 with commit 7e4d784f5810bba76c4593791028e13cce4af547 and fixed in 6.16-rc1 with commit feafc73f3e6ae73371777a037d41d2e31c929636

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-2025-38271
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/core/rtnetlink.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/8a29ae8428a5c26f0b4471c2057d9e9415c53109
	https://git.kernel.org/stable/c/feafc73f3e6ae73371777a037d41d2e31c929636