CVE-2021-47116: ext4: fix memory leak in ext4_mb_init_backend on error path.

CVE-2021-47116: ext4: fix memory leak in ext4_mb_init_backend on error path.

[Greg Kroah-Hartman]

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

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

ext4: fix memory leak in ext4_mb_init_backend on error path.

Fix a memory leak discovered by syzbot when a file system is corrupted
with an illegally large s_log_groups_per_flex.

The Linux kernel CVE team has assigned CVE-2021-47116 to this issue.


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

	Fixed in 5.10.43 with commit 2050c6e5b161
	Fixed in 5.12.10 with commit 04fb2baa0b14
	Fixed in 5.13 with commit a8867f4e3809

Please see https://www.kernel.org or 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-2021-47116
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:
	fs/ext4/mballoc.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/2050c6e5b161e5e25ce3c420fef58b24fa388a49
	https://git.kernel.org/stable/c/04fb2baa0b147f51db065a1b13a11954abe592d0
	https://git.kernel.org/stable/c/a8867f4e3809050571c98de7a2d465aff5e4daf5