linux-cve-announce - CVE-2025-38465: netlink: Fix wraparounds of sk->sk_rmem

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Message-ID: <2025072508-CVE-2025-38465-28ad@gregkh>
Date: Fri, 25 Jul 2025 17:28:27 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38465: netlink: Fix wraparounds of sk->sk_rmem_alloc.

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

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

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

netlink: Fix wraparounds of sk->sk_rmem_alloc.

Netlink has this pattern in some places

  if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf)
  	atomic_add(skb->truesize, &sk->sk_rmem_alloc);

, which has the same problem fixed by commit 5a465a0da13e ("udp:
Fix multiple wraparounds of sk->sk_rmem_alloc.").

For example, if we set INT_MAX to SO_RCVBUFFORCE, the condition
is always false as the two operands are of int.

Then, a single socket can eat as many skb as possible until OOM
happens, and we can see multiple wraparounds of sk->sk_rmem_alloc.

Let's fix it by using atomic_add_return() and comparing the two
variables as unsigned int.

Before:
  [root@...ora ~]# ss -f netlink
  Recv-Q      Send-Q Local Address:Port                Peer Address:Port
  -1668710080 0               rtnl:nl_wraparound/293               *

After:
  [root@...ora ~]# ss -f netlink
  Recv-Q     Send-Q Local Address:Port                Peer Address:Port
  2147483072 0               rtnl:nl_wraparound/290               *
  ^
  `--- INT_MAX - 576

The Linux kernel CVE team has assigned CVE-2025-38465 to this issue.


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

	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.4.296 with commit 9da025150b7c14a8390fc06aea314c0a4011e82c
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.10.240 with commit c4ceaac5c5ba0b992ee1dc88e2a02421549e5c98
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.15.189 with commit fd69af06101090eaa60b3d216ae715f9c0a58e5b
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.1.146 with commit 76602d8e13864524382b0687dc32cd8f19164d5a
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.99 with commit 55baecb9eb90238f60a8350660d6762046ebd3bd
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.39 with commit 4b8e18af7bea92f8b7fb92d40aeae729209db250
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.15.7 with commit cd7ff61bfffd7000143c42bbffb85eeb792466d6
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.16-rc6 with commit ae8f160e7eb24240a2a79fc4c815c6a0d4ee16cc

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-2025-38465
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/9da025150b7c14a8390fc06aea314c0a4011e82c
	https://git.kernel.org/stable/c/c4ceaac5c5ba0b992ee1dc88e2a02421549e5c98
	https://git.kernel.org/stable/c/fd69af06101090eaa60b3d216ae715f9c0a58e5b
	https://git.kernel.org/stable/c/76602d8e13864524382b0687dc32cd8f19164d5a
	https://git.kernel.org/stable/c/55baecb9eb90238f60a8350660d6762046ebd3bd
	https://git.kernel.org/stable/c/4b8e18af7bea92f8b7fb92d40aeae729209db250
	https://git.kernel.org/stable/c/cd7ff61bfffd7000143c42bbffb85eeb792466d6
	https://git.kernel.org/stable/c/ae8f160e7eb24240a2a79fc4c815c6a0d4ee16cc