linux-cve-announce - CVE-2025-68373: md: avoid repeated calls to del

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Message-ID: <2025122401-CVE-2025-68373-c983@gregkh>
Date: Wed, 24 Dec 2025 11:35:18 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-68373: md: avoid repeated calls to del_gendisk

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

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

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

md: avoid repeated calls to del_gendisk

There is a uaf problem which is found by case 23rdev-lifetime:

Oops: general protection fault, probably for non-canonical address 0xdead000000000122
RIP: 0010:bdi_unregister+0x4b/0x170
Call Trace:
 <TASK>
 __del_gendisk+0x356/0x3e0
 mddev_unlock+0x351/0x360
 rdev_attr_store+0x217/0x280
 kernfs_fop_write_iter+0x14a/0x210
 vfs_write+0x29e/0x550
 ksys_write+0x74/0xf0
 do_syscall_64+0xbb/0x380
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff5250a177e

The sequence is:
1. rdev remove path gets reconfig_mutex
2. rdev remove path release reconfig_mutex in mddev_unlock
3. md stop calls do_md_stop and sets MD_DELETED
4. rdev remove path calls del_gendisk because MD_DELETED is set
5. md stop path release reconfig_mutex and calls del_gendisk again

So there is a race condition we should resolve. This patch adds a
flag MD_DO_DELETE to avoid the race condition.

The Linux kernel CVE team has assigned CVE-2025-68373 to this issue.


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

	Issue introduced in 6.17 with commit 9e59d609763f70a992a8f3808dabcce60f14eb5c and fixed in 6.17.13 with commit b4c5cf406062ad44cd178269571530c6435b2f3b
	Issue introduced in 6.17 with commit 9e59d609763f70a992a8f3808dabcce60f14eb5c and fixed in 6.18.2 with commit f0fae1debeb9102398ddf2ef69b4f5d395afafed
	Issue introduced in 6.17 with commit 9e59d609763f70a992a8f3808dabcce60f14eb5c and fixed in 6.19-rc1 with commit 90e3bb44c0a86e245d8e5c6520206fa113acb1ee

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-2025-68373
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/md/md.c
	drivers/md/md.h


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/b4c5cf406062ad44cd178269571530c6435b2f3b
	https://git.kernel.org/stable/c/f0fae1debeb9102398ddf2ef69b4f5d395afafed
	https://git.kernel.org/stable/c/90e3bb44c0a86e245d8e5c6520206fa113acb1ee