linux-cve-announce - CVE-2025-38150: af_packet: move notifier's packet_dev

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Message-ID: <2025070336-CVE-2025-38150-3ce8@gregkh>
Date: Thu,  3 Jul 2025 10:36:07 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38150: af_packet: move notifier's packet_dev_mc out of rcu critical section

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

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

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

af_packet: move notifier's packet_dev_mc out of rcu critical section

Syzkaller reports the following issue:

 BUG: sleeping function called from invalid context at kernel/locking/mutex.c:578
 __mutex_lock+0x106/0xe80 kernel/locking/mutex.c:746
 team_change_rx_flags+0x38/0x220 drivers/net/team/team_core.c:1781
 dev_change_rx_flags net/core/dev.c:9145 [inline]
 __dev_set_promiscuity+0x3f8/0x590 net/core/dev.c:9189
 netif_set_promiscuity+0x50/0xe0 net/core/dev.c:9201
 dev_set_promiscuity+0x126/0x260 net/core/dev_api.c:286 packet_dev_mc net/packet/af_packet.c:3698 [inline]
 packet_dev_mclist_delete net/packet/af_packet.c:3722 [inline]
 packet_notifier+0x292/0xa60 net/packet/af_packet.c:4247
 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
 call_netdevice_notifiers net/core/dev.c:2228 [inline]
 unregister_netdevice_many_notify+0x15d8/0x2330 net/core/dev.c:11972
 rtnl_delete_link net/core/rtnetlink.c:3522 [inline]
 rtnl_dellink+0x488/0x710 net/core/rtnetlink.c:3564
 rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6955
 netlink_rcv_skb+0x219/0x490 net/netlink/af_netlink.c:2534

Calling `PACKET_ADD_MEMBERSHIP` on an ops-locked device can trigger
the `NETDEV_UNREGISTER` notifier, which may require disabling promiscuous
and/or allmulti mode. Both of these operations require acquiring
the netdev instance lock.

Move the call to `packet_dev_mc` outside of the RCU critical section.
The `mclist` modifications (add, del, flush, unregister) are protected by
the RTNL, not the RCU. The RCU only protects the `sklist` and its
associated `sks`. The delayed operation on the `mclist` entry remains
within the RTNL.

The Linux kernel CVE team has assigned CVE-2025-38150 to this issue.


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

	Issue introduced in 6.15 with commit ad7c7b2172c388818a111455643491d75f535e90 and fixed in 6.15.3 with commit 2dd4781c5af99415ebbd2f7cc763feb109863c05
	Issue introduced in 6.15 with commit ad7c7b2172c388818a111455643491d75f535e90 and fixed in 6.16-rc1 with commit d8d85ef0a631df9127f202e6371bb33a0b589952

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-2025-38150
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/packet/af_packet.c
	net/packet/internal.h


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/2dd4781c5af99415ebbd2f7cc763feb109863c05
	https://git.kernel.org/stable/c/d8d85ef0a631df9127f202e6371bb33a0b589952