linux-cve-announce - CVE-2025-21954: netmem: prevent TX of unreadable skbs

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Message-ID: <2025040143-CVE-2025-21954-8f0d@gregkh>
Date: Tue,  1 Apr 2025 16:45:39 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21954: netmem: prevent TX of unreadable skbs

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

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

netmem: prevent TX of unreadable skbs

Currently on stable trees we have support for netmem/devmem RX but not
TX. It is not safe to forward/redirect an RX unreadable netmem packet
into the device's TX path, as the device may call dma-mapping APIs on
dma addrs that should not be passed to it.

Fix this by preventing the xmit of unreadable skbs.

Tested by configuring tc redirect:

sudo tc qdisc add dev eth1 ingress
sudo tc filter add dev eth1 ingress protocol ip prio 1 flower ip_proto \
	tcp src_ip 192.168.1.12 action mirred egress redirect dev eth1

Before, I see unreadable skbs in the driver's TX path passed to dma
mapping APIs.

After, I don't see unreadable skbs in the driver's TX path passed to dma
mapping APIs.

The Linux kernel CVE team has assigned CVE-2025-21954 to this issue.


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

	Issue introduced in 6.12 with commit 65249feb6b3df9e17bab5911ee56fa7b0971e231 and fixed in 6.12.20 with commit 454825019d2f0c59e5174ece9e713f45ad80beff
	Issue introduced in 6.12 with commit 65249feb6b3df9e17bab5911ee56fa7b0971e231 and fixed in 6.13.8 with commit 1c17c8ced25c5fbe424c7ad7ea11d33014a986b1
	Issue introduced in 6.12 with commit 65249feb6b3df9e17bab5911ee56fa7b0971e231 and fixed in 6.14 with commit f3600c867c99a2cc8038680ecf211089c50e7971

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-2025-21954
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/dev.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/454825019d2f0c59e5174ece9e713f45ad80beff
	https://git.kernel.org/stable/c/1c17c8ced25c5fbe424c7ad7ea11d33014a986b1
	https://git.kernel.org/stable/c/f3600c867c99a2cc8038680ecf211089c50e7971