linux-cve-announce - CVE-2026-23201: ceph: fix oops due to invalid pointer for kfree() in parse

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Message-ID: <2026021436-CVE-2026-23201-4530@gregkh>
Date: Sat, 14 Feb 2026 17:28:58 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23201: ceph: fix oops due to invalid pointer for kfree() in parse_longname()

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

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

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

ceph: fix oops due to invalid pointer for kfree() in parse_longname()

This fixes a kernel oops when reading ceph snapshot directories (.snap),
for example by simply running `ls /mnt/my_ceph/.snap`.

The variable str is guarded by __free(kfree), but advanced by one for
skipping the initial '_' in snapshot names. Thus, kfree() is called
with an invalid pointer.  This patch removes the need for advancing the
pointer so kfree() is called with correct memory pointer.

Steps to reproduce:

1. Create snapshots on a cephfs volume (I've 63 snaps in my testcase)

2. Add cephfs mount to fstab
$ echo "samba-fileserver@...les=/volumes/datapool/stuff/3461082b-ecc9-4e82-8549-3fd2590d3fb6      /mnt/test/stuff   ceph     acl,noatime,_netdev    0       0" >> /etc/fstab

3. Reboot the system
$ systemctl reboot

4. Check if it's really mounted
$ mount | grep stuff

5. List snapshots (expected 63 snapshots on my system)
$ ls /mnt/test/stuff/.snap

Now ls hangs forever and the kernel log shows the oops.

The Linux kernel CVE team has assigned CVE-2026-23201 to this issue.


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

	Issue introduced in 6.12.42 with commit bb80f7618832d26f7e395f52f82b1dac76223e5f and fixed in 6.12.70 with commit 8c9af7339de419819cfc641d551675d38ff99abf
	Issue introduced in 6.17 with commit 101841c38346f4ca41dc1802c867da990ffb32eb and fixed in 6.18.10 with commit e258ed369c9e04caa7d2fd49785d753ae4034cb6
	Issue introduced in 6.17 with commit 101841c38346f4ca41dc1802c867da990ffb32eb and fixed in 6.19 with commit bc8dedae022ce3058659c3addef3ec4b41d15e00
	Issue introduced in 6.15.10 with commit 3145b2b11492d61c512bbc59660bb823bc757f48
	Issue introduced in 6.16.1 with commit 493479af8af3ab907f49e99323777d498a4fbd2b

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-2026-23201
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/ceph/crypto.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/8c9af7339de419819cfc641d551675d38ff99abf
	https://git.kernel.org/stable/c/e258ed369c9e04caa7d2fd49785d753ae4034cb6
	https://git.kernel.org/stable/c/bc8dedae022ce3058659c3addef3ec4b41d15e00