Subject: CVE-2021-47357: atm: iphase: fix possible use-after-free in ia_module_exit()

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

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

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

atm: iphase: fix possible use-after-free in ia_module_exit()

This module's remove path calls del_timer(). However, that function
does not wait until the timer handler finishes. This means that the
timer handler may still be running after the driver's remove function
has finished, which would result in a use-after-free.

Fix by calling del_timer_sync(), which makes sure the timer handler
has finished, and unable to re-schedule itself.

The Linux kernel CVE team has assigned CVE-2021-47357 to this issue.

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

	Fixed in 4.4.276 with commit 9e1616878551
	Fixed in 4.9.276 with commit a832ee2f2145
	Fixed in 4.14.240 with commit bcdd2be48edd
	Fixed in 4.19.198 with commit 89ce0b0747f3
	Fixed in 5.4.133 with commit c9172498d4d6
	Fixed in 5.10.51 with commit e759ff76ebbb
	Fixed in 5.12.18 with commit b58d246a058a
	Fixed in 5.13.3 with commit d1fb12412874
	Fixed in 5.14 with commit 1c72e6ab66b9

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-2021-47357
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/atm/iphase.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/9e161687855175334ca93c6c3ccb221731194479
	https://git.kernel.org/stable/c/a832ee2f2145f57443b2d565f8cb5490e8339f42
	https://git.kernel.org/stable/c/bcdd2be48edd8c6867fb44112cb8d18086beae29
	https://git.kernel.org/stable/c/89ce0b0747f319eb70f85bc820dcc43cebbd5417
	https://git.kernel.org/stable/c/c9172498d4d62c9b64e5fb37c1ee0343e65fe51b
	https://git.kernel.org/stable/c/e759ff76ebbbfcdcf83b6634c54dc47828573d8b
	https://git.kernel.org/stable/c/b58d246a058ae88484758cd4ab27b3180fd5ecf8
	https://git.kernel.org/stable/c/d1fb12412874c94ad037e11d0ecdd1140a439297
	https://git.kernel.org/stable/c/1c72e6ab66b9598cac741ed397438a52065a8f1f