CVE-2021-47096: ALSA: rawmidi - fix the uninitalized user_pversion

CVE-2021-47096: ALSA: rawmidi - fix the uninitalized user_pversion

[Greg Kroah-Hartman]

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

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

ALSA: rawmidi - fix the uninitalized user_pversion

The user_pversion was uninitialized for the user space file structure
in the open function, because the file private structure use
kmalloc for the allocation.

The kernel ALSA sequencer code clears the file structure, so no additional
fixes are required.

BugLink: https://github.com/alsa-project/alsa-lib/issues/178

The Linux kernel CVE team has assigned CVE-2021-47096 to this issue.


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

	Issue introduced in 5.15 with commit 09d23174402d and fixed in 5.15.12 with commit b398fcbe4de1
	Issue introduced in 5.15 with commit 09d23174402d and fixed in 5.16 with commit 39a8fc4971a0

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-2021-47096
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:
	sound/core/rawmidi.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/b398fcbe4de1e1100867fdb6f447c6fbc8fe7085
	https://git.kernel.org/stable/c/39a8fc4971a00d22536aeb7d446ee4a97810611b