linux-cve-announce - CVE-2025-38247: userns and mnt_idmap leak in open_tree

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Message-ID: <2025070934-CVE-2025-38247-14ac@gregkh>
Date: Wed,  9 Jul 2025 12:42:39 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38247: userns and mnt_idmap leak in open_tree_attr(2)

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

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

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

userns and mnt_idmap leak in open_tree_attr(2)

Once want_mount_setattr() has returned a positive, it does require
finish_mount_kattr() to release ->mnt_userns.  Failing do_mount_setattr()
does not change that.

As the result, we can end up leaking userns and possibly mnt_idmap as
well.

The Linux kernel CVE team has assigned CVE-2025-38247 to this issue.


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

	Issue introduced in 6.15 with commit c4a16820d90199409c9bf01c4f794e1e9e8d8fd8 and fixed in 6.15.5 with commit 142db4e76110dd80239f4e79810f85ea1735ad60
	Issue introduced in 6.15 with commit c4a16820d90199409c9bf01c4f794e1e9e8d8fd8 and fixed in 6.16-rc4 with commit 0748e553df0225754c316a92af3a77fdc057b358

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-2025-38247
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:
	fs/namespace.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/142db4e76110dd80239f4e79810f85ea1735ad60
	https://git.kernel.org/stable/c/0748e553df0225754c316a92af3a77fdc057b358