linux-cve-announce - CVE-2025-39861: Bluetooth: vhci: Prevent use-after-free by removing debugfs files early

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Message-ID: <2025091906-CVE-2025-39861-5ba5@gregkh>
Date: Fri, 19 Sep 2025 17:28:25 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39861: Bluetooth: vhci: Prevent use-after-free by removing debugfs files early

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

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

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

Bluetooth: vhci: Prevent use-after-free by removing debugfs files early

Move the creation of debugfs files into a dedicated function, and ensure
they are explicitly removed during vhci_release(), before associated
data structures are freed.

Previously, debugfs files such as "force_suspend", "force_wakeup", and
others were created under hdev->debugfs but not removed in
vhci_release(). Since vhci_release() frees the backing vhci_data
structure, any access to these files after release would result in
use-after-free errors.

Although hdev->debugfs is later freed in hci_release_dev(), user can
access files after vhci_data is freed but before hdev->debugfs is
released.

The Linux kernel CVE team has assigned CVE-2025-39861 to this issue.


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

	Issue introduced in 6.4 with commit ab4e4380d4e158486e595013a2635190e07e28ce and fixed in 6.6.105 with commit bd75eba88e88d7b896b0c737b02a74a12afc235f
	Issue introduced in 6.4 with commit ab4e4380d4e158486e595013a2635190e07e28ce and fixed in 6.12.46 with commit 1503756fffe76d5aea2371a4b8dee20c3577bcfd
	Issue introduced in 6.4 with commit ab4e4380d4e158486e595013a2635190e07e28ce and fixed in 6.16.6 with commit 7cc08f2f127b9a66f46ea918e34353811a7cb378
	Issue introduced in 6.4 with commit ab4e4380d4e158486e595013a2635190e07e28ce and fixed in 6.17-rc5 with commit 28010791193a4503f054e8d69a950ef815deb539

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-2025-39861
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/bluetooth/hci_vhci.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/bd75eba88e88d7b896b0c737b02a74a12afc235f
	https://git.kernel.org/stable/c/1503756fffe76d5aea2371a4b8dee20c3577bcfd
	https://git.kernel.org/stable/c/7cc08f2f127b9a66f46ea918e34353811a7cb378
	https://git.kernel.org/stable/c/28010791193a4503f054e8d69a950ef815deb539