linux-cve-announce - CVE-2022-50477: rtc: class: Fix potential memleak in devm_rtc_allocate

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Message-ID: <2025100438-CVE-2022-50477-1815@gregkh>
Date: Sat,  4 Oct 2025 17:16:36 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50477: rtc: class: Fix potential memleak in devm_rtc_allocate_device()

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

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

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

rtc: class: Fix potential memleak in devm_rtc_allocate_device()

devm_rtc_allocate_device() will alloc a rtc_device first, and then run
dev_set_name(). If dev_set_name() failed, the rtc_device will memleak.
Move devm_add_action_or_reset() in front of dev_set_name() to prevent
memleak.

unreferenced object 0xffff888110a53000 (size 2048):
  comm "python3", pid 470, jiffies 4296078308 (age 58.882s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 08 30 a5 10 81 88 ff ff  .........0......
    08 30 a5 10 81 88 ff ff 00 00 00 00 00 00 00 00  .0..............
  backtrace:
    [<000000004aac0364>] kmalloc_trace+0x21/0x110
    [<000000000ff02202>] devm_rtc_allocate_device+0xd4/0x400
    [<000000001bdf5639>] devm_rtc_device_register+0x1a/0x80
    [<00000000351bf81c>] rx4581_probe+0xdd/0x110 [rtc_rx4581]
    [<00000000f0eba0ae>] spi_probe+0xde/0x130
    [<00000000bff89ee8>] really_probe+0x175/0x3f0
    [<00000000128e8d84>] __driver_probe_device+0xe6/0x170
    [<00000000ee5bf913>] device_driver_attach+0x32/0x80
    [<00000000f3f28f92>] bind_store+0x10b/0x1a0
    [<000000009ff812d8>] drv_attr_store+0x49/0x70
    [<000000008139c323>] sysfs_kf_write+0x8d/0xb0
    [<00000000b6146e01>] kernfs_fop_write_iter+0x214/0x2d0
    [<00000000ecbe3895>] vfs_write+0x61a/0x7d0
    [<00000000aa2196ea>] ksys_write+0xc8/0x190
    [<0000000046a600f5>] do_syscall_64+0x37/0x90
    [<00000000541a336f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

The Linux kernel CVE team has assigned CVE-2022-50477 to this issue.


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

	Issue introduced in 5.16 with commit 24d23181e43d72ca692a479e70dfe5b0b5dd33f1 and fixed in 6.0.16 with commit 0bcfc8fd3e596994f527b46730579428b3a4fa5f
	Issue introduced in 5.16 with commit 24d23181e43d72ca692a479e70dfe5b0b5dd33f1 and fixed in 6.1.2 with commit 59457a0f079eae19aaf322b3cc1c8ba66f55c5f3
	Issue introduced in 5.16 with commit 24d23181e43d72ca692a479e70dfe5b0b5dd33f1 and fixed in 6.2 with commit 60da73808298ff2cfa9f165d55eb3d7aa7078601

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-2022-50477
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/rtc/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/0bcfc8fd3e596994f527b46730579428b3a4fa5f
	https://git.kernel.org/stable/c/59457a0f079eae19aaf322b3cc1c8ba66f55c5f3
	https://git.kernel.org/stable/c/60da73808298ff2cfa9f165d55eb3d7aa7078601