Subject: CVE-2021-47455: ptp: Fix possible memory leak in ptp_clock_register()

From: Greg Kroah-Hartman <[email-masked]>

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

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

ptp: Fix possible memory leak in ptp_clock_register()

I got memory leak as follows when doing fault injection test:

unreferenced object 0xffff88800906c618 (size 8):
  comm "i2c-idt82p33931", pid 4421, jiffies 4294948083 (age 13.188s)
  hex dump (first 8 bytes):
    70 74 70 30 00 00 00 00                          ptp0....
  backtrace:
    [<00000000312ed458>] __kmalloc_track_caller+0x19f/0x3a0
    [<0000000079f6e2ff>] kvasprintf+0xb5/0x150
    [<0000000026aae54f>] kvasprintf_const+0x60/0x190
    [<00000000f323a5f7>] kobject_set_name_vargs+0x56/0x150
    [<000000004e35abdd>] dev_set_name+0xc0/0x100
    [<00000000f20cfe25>] ptp_clock_register+0x9f4/0xd30 [ptp]
    [<000000008bb9f0de>] idt82p33_probe.cold+0x8b6/0x1561 [ptp_idt82p33]

When posix_clock_register() returns an error, the name allocated
in dev_set_name() will be leaked, the put_device() should be used
to give up the device reference, then the name will be freed in
kobject_cleanup() and other memory will be freed in ptp_clock_release().

The Linux kernel CVE team has assigned CVE-2021-47455 to this issue.

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

	Issue introduced in 5.5 with commit a33121e5487b and fixed in 5.14.15 with commit 95c0a0c5ec88
	Issue introduced in 5.5 with commit a33121e5487b and fixed in 5.15 with commit 4225fea1cb28
	Issue introduced in 3.16.83 with commit 5230ef61882d
	Issue introduced in 4.4.224 with commit 6f5e3bb7879e
	Issue introduced in 4.9.224 with commit 89e8fc989fea
	Issue introduced in 4.14.162 with commit 2dece4d6d13f
	Issue introduced in 4.19.93 with commit 0393b8720128
	Issue introduced in 5.4.8 with commit bfa2e0cd3dfd

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-2021-47455
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/ptp/ptp_clock.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/95c0a0c5ec8839f8f21672be786e87a100319ca8
	https://git.kernel.org/stable/c/4225fea1cb28370086e17e82c0f69bec2779dca0