linux-cve-announce - CVE-2022-50578: class: fix possible memory leak in __class

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Message-ID: <2025102209-CVE-2022-50578-eb90@gregkh>
Date: Wed, 22 Oct 2025 15:24:26 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50578: class: fix possible memory leak in __class_register()

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

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

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

class: fix possible memory leak in __class_register()

If class_add_groups() returns error, the 'cp->subsys' need be
unregister, and the 'cp' need be freed.

We can not call kset_unregister() here, because the 'cls' will
be freed in callback function class_release() and it's also
freed in caller's error path, it will cause double free.

So fix this by calling kobject_del() and kfree_const(name) to
cleanup kobject. Besides, call kfree() to free the 'cp'.

Fault injection test can trigger this:

unreferenced object 0xffff888102fa8190 (size 8):
  comm "modprobe", pid 502, jiffies 4294906074 (age 49.296s)
  hex dump (first 8 bytes):
    70 6b 74 63 64 76 64 00                          pktcdvd.
  backtrace:
    [<00000000e7c7703d>] __kmalloc_track_caller+0x1ae/0x320
    [<000000005e4d70bc>] kstrdup+0x3a/0x70
    [<00000000c2e5e85a>] kstrdup_const+0x68/0x80
    [<000000000049a8c7>] kvasprintf_const+0x10b/0x190
    [<0000000029123163>] kobject_set_name_vargs+0x56/0x150
    [<00000000747219c9>] kobject_set_name+0xab/0xe0
    [<0000000005f1ea4e>] __class_register+0x15c/0x49a

unreferenced object 0xffff888037274000 (size 1024):
  comm "modprobe", pid 502, jiffies 4294906074 (age 49.296s)
  hex dump (first 32 bytes):
    00 40 27 37 80 88 ff ff 00 40 27 37 80 88 ff ff  .@.......@......
    00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00  .....N..........
  backtrace:
    [<00000000151f9600>] kmem_cache_alloc_trace+0x17c/0x2f0
    [<00000000ecf3dd95>] __class_register+0x86/0x49a

The Linux kernel CVE team has assigned CVE-2022-50578 to this issue.


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

	Issue introduced in 4.10 with commit ced6473e7486702f530a49f886b73195e4977734 and fixed in 4.14.303 with commit 4efa5443817c1b6de22d401aeca5b2481e835f8c
	Issue introduced in 4.10 with commit ced6473e7486702f530a49f886b73195e4977734 and fixed in 4.19.270 with commit 3bb9c92c27624ad076419a70f2b1a30cd1f8bbbd
	Issue introduced in 4.10 with commit ced6473e7486702f530a49f886b73195e4977734 and fixed in 5.4.229 with commit 3e0efc3f3f5e5c73996782f8db69963e501bb878
	Issue introduced in 4.10 with commit ced6473e7486702f530a49f886b73195e4977734 and fixed in 5.10.163 with commit 18a7200646958cf8e1b8a933de08122fc50676cd
	Issue introduced in 4.10 with commit ced6473e7486702f530a49f886b73195e4977734 and fixed in 5.15.86 with commit 417ef049e3fd3b0d2593c1d5ffa3d0d5d0a018a7
	Issue introduced in 4.10 with commit ced6473e7486702f530a49f886b73195e4977734 and fixed in 6.0.16 with commit e764ad5918a099ebeb909ccff83893a714e497e1
	Issue introduced in 4.10 with commit ced6473e7486702f530a49f886b73195e4977734 and fixed in 6.1.2 with commit abaedb68a769e6bf36836b55a2f49b531c5f3f7b
	Issue introduced in 4.10 with commit ced6473e7486702f530a49f886b73195e4977734 and fixed in 6.2 with commit 8c3e8a6bdb5253b97ad532570f8b5db5f7a06407

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-2022-50578
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/base/class.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/4efa5443817c1b6de22d401aeca5b2481e835f8c
	https://git.kernel.org/stable/c/3bb9c92c27624ad076419a70f2b1a30cd1f8bbbd
	https://git.kernel.org/stable/c/3e0efc3f3f5e5c73996782f8db69963e501bb878
	https://git.kernel.org/stable/c/18a7200646958cf8e1b8a933de08122fc50676cd
	https://git.kernel.org/stable/c/417ef049e3fd3b0d2593c1d5ffa3d0d5d0a018a7
	https://git.kernel.org/stable/c/e764ad5918a099ebeb909ccff83893a714e497e1
	https://git.kernel.org/stable/c/abaedb68a769e6bf36836b55a2f49b531c5f3f7b
	https://git.kernel.org/stable/c/8c3e8a6bdb5253b97ad532570f8b5db5f7a06407