linux-cve-announce - CVE-2025-21758: ipv6: mcast: add RCU protection to mld

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Message-ID: <2025022604-CVE-2025-21758-9f8c@gregkh>
Date: Wed, 26 Feb 2025 18:17:14 -0800
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21758: ipv6: mcast: add RCU protection to mld_newpack()

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

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

ipv6: mcast: add RCU protection to mld_newpack()

mld_newpack() can be called without RTNL or RCU being held.

Note that we no longer can use sock_alloc_send_skb() because
ipv6.igmp_sk uses GFP_KERNEL allocations which can sleep.

Instead use alloc_skb() and charge the net->ipv6.igmp_sk
socket under RCU protection.

The Linux kernel CVE team has assigned CVE-2025-21758 to this issue.


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

	Issue introduced in 2.6.26 with commit b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 and fixed in 6.1.129 with commit e8af3632a7f2da83e27b083f787bced1faba00b1
	Issue introduced in 2.6.26 with commit b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 and fixed in 6.6.79 with commit 1b91c597b0214b1b462eb627ec02658c944623f2
	Issue introduced in 2.6.26 with commit b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 and fixed in 6.12.16 with commit 25195f9d5ffcc8079ad743a50c0409dbdc48d98a
	Issue introduced in 2.6.26 with commit b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 and fixed in 6.13.4 with commit d60d493b0e65647e0335e6a7c4547abcea7df8e9
	Issue introduced in 2.6.26 with commit b8ad0cbc58f703972e9e37c4e2a8081dd7e6a551 and fixed in 6.14-rc3 with commit a527750d877fd334de87eef81f1cb5f0f0ca3373

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-2025-21758
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/ipv6/mcast.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/e8af3632a7f2da83e27b083f787bced1faba00b1
	https://git.kernel.org/stable/c/1b91c597b0214b1b462eb627ec02658c944623f2
	https://git.kernel.org/stable/c/25195f9d5ffcc8079ad743a50c0409dbdc48d98a
	https://git.kernel.org/stable/c/d60d493b0e65647e0335e6a7c4547abcea7df8e9
	https://git.kernel.org/stable/c/a527750d877fd334de87eef81f1cb5f0f0ca3373