Subject: CVE-2022-48994: ALSA: seq: Fix function prototype mismatch in snd_seq_expand_var_event

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

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

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

ALSA: seq: Fix function prototype mismatch in snd_seq_expand_var_event

With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
indirect call targets are validated against the expected function
pointer prototype to make sure the call target is valid to help mitigate
ROP attacks. If they are not identical, there is a failure at run time,
which manifests as either a kernel panic or thread getting killed.

seq_copy_in_user() and seq_copy_in_kernel() did not have prototypes
matching snd_seq_dump_func_t. Adjust this and remove the casts. There
are not resulting binary output differences.

This was found as a result of Clang's new -Wcast-function-type-strict
flag, which is more sensitive than the simpler -Wcast-function-type,
which only checks for type width mismatches.

The Linux kernel CVE team has assigned CVE-2022-48994 to this issue.

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

	Fixed in 4.9.336 with commit b38486e82ecb
	Fixed in 4.14.302 with commit e385360705a0
	Fixed in 4.19.269 with commit 2f46e95bf344
	Fixed in 5.4.227 with commit 63badfed2002
	Fixed in 5.10.159 with commit 15c42ab8d43a
	Fixed in 5.15.83 with commit fccd454129f6
	Fixed in 6.0.13 with commit 13ee8fb5410b
	Fixed in 6.1 with commit 05530ef7cf7c

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-2022-48994
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/seq/seq_memory.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/b38486e82ecb9f3046e0184205f6b61408fc40c9
	https://git.kernel.org/stable/c/e385360705a0b346bdb57ce938249175d0613b8a
	https://git.kernel.org/stable/c/2f46e95bf344abc4e74f8158901d32a869e0adb6
	https://git.kernel.org/stable/c/63badfed200219ca656968725f1a43df293ac936
	https://git.kernel.org/stable/c/15c42ab8d43acb73e2eba361ad05822c0af0ecfa
	https://git.kernel.org/stable/c/fccd454129f6a0739651f7f58307cdb631fd6e89
	https://git.kernel.org/stable/c/13ee8fb5410b740c8dd2867d3557c7662f7dda2d
	https://git.kernel.org/stable/c/05530ef7cf7c7d700f6753f058999b1b5099a026