linux-cve-announce - CVE-2025-68376: coresight: ETR: Fix ETR buffer use-after-free issue

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Message-ID: <2025122402-CVE-2025-68376-a954@gregkh>
Date: Wed, 24 Dec 2025 11:35:21 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-68376: coresight: ETR: Fix ETR buffer use-after-free issue

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

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

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

coresight: ETR: Fix ETR buffer use-after-free issue

When ETR is enabled as CS_MODE_SYSFS, if the buffer size is changed
and enabled again, currently sysfs_buf will point to the newly
allocated memory(buf_new) and free the old memory(buf_old). But the
etr_buf that is being used by the ETR remains pointed to buf_old, not
updated to buf_new. In this case, it will result in a memory
use-after-free issue.

Fix this by checking ETR's mode before updating and releasing buf_old,
if the mode is CS_MODE_SYSFS, then skip updating and releasing it.

The Linux kernel CVE team has assigned CVE-2025-68376 to this issue.


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

	Issue introduced in 6.6 with commit bd2767ec3df2775bc336f441f9068a989ccb919d and fixed in 6.17.13 with commit 70acbc9c77686b7a521af6d7a543dcd9c324cf07
	Issue introduced in 6.6 with commit bd2767ec3df2775bc336f441f9068a989ccb919d and fixed in 6.18.2 with commit cda077a19f5c8d6ec61e5b97deca203d95e3a422
	Issue introduced in 6.6 with commit bd2767ec3df2775bc336f441f9068a989ccb919d and fixed in 6.19-rc1 with commit 35501ac3c7d40a7bb9568c2f89d6b56beaf9bed3
	Issue introduced in 6.5.8 with commit fdd3ceb0001da6768bede9779a0190a42e65c404

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-2025-68376
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:
	drivers/hwtracing/coresight/coresight-tmc-etr.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/70acbc9c77686b7a521af6d7a543dcd9c324cf07
	https://git.kernel.org/stable/c/cda077a19f5c8d6ec61e5b97deca203d95e3a422
	https://git.kernel.org/stable/c/35501ac3c7d40a7bb9568c2f89d6b56beaf9bed3