linux-cve-announce - CVE-2025-38432: net: netpoll: Initialize UDP checksum field before checksumming

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Message-ID: <2025072516-CVE-2025-38432-ce36@gregkh>
Date: Fri, 25 Jul 2025 16:24:17 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38432: net: netpoll: Initialize UDP checksum field before checksumming

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

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

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

net: netpoll: Initialize UDP checksum field before checksumming

commit f1fce08e63fe ("netpoll: Eliminate redundant assignment") removed
the initialization of the UDP checksum, which was wrong and broke
netpoll IPv6 transmission due to bad checksumming.

udph->check needs to be set before calling csum_ipv6_magic().

The Linux kernel CVE team has assigned CVE-2025-38432 to this issue.


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

	Issue introduced in 6.15 with commit f1fce08e63fe1a2a8b8106b93b7244a39830edae and fixed in 6.15.5 with commit 353016ec159f939a380ff6746476a779367ba9a3
	Issue introduced in 6.15 with commit f1fce08e63fe1a2a8b8106b93b7244a39830edae and fixed in 6.16-rc4 with commit f5990207026987a353d5a95204c4d9cb725637fd

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-2025-38432
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/netpoll.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/353016ec159f939a380ff6746476a779367ba9a3
	https://git.kernel.org/stable/c/f5990207026987a353d5a95204c4d9cb725637fd