Subject: CVE-2022-48702: ALSA: emu10k1: Fix out of bounds access in snd_emu10k1_pcm_channel_alloc()

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

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

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

ALSA: emu10k1: Fix out of bounds access in snd_emu10k1_pcm_channel_alloc()

The voice allocator sometimes begins allocating from near the end of the
array and then wraps around, however snd_emu10k1_pcm_channel_alloc()
accesses the newly allocated voices as if it never wrapped around.

This results in out of bounds access if the first voice has a high enough
index so that first_voice + requested_voice_count > NUM_G (64).
The more voices are requested, the more likely it is for this to occur.

This was initially discovered using PipeWire, however it can be reproduced
by calling aplay multiple times with 16 channels:
aplay -r 48000 -D plughw:CARD=Live,DEV=3 -c 16 /dev/zero

UBSAN: array-index-out-of-bounds in sound/pci/emu10k1/emupcm.c:127:40
index 65 is out of range for type 'snd_emu10k1_voice [64]'
CPU: 1 PID: 31977 Comm: aplay Tainted: G        W IOE      6.0.0-rc2-emu10k1+ #7
Hardware name: ASUSTEK COMPUTER INC P5W DH Deluxe/P5W DH Deluxe, BIOS 3002    07/22/2010
Call Trace:
<TASK>
dump_stack_lvl+0x49/0x63
dump_stack+0x10/0x16
ubsan_epilogue+0x9/0x3f
__ubsan_handle_out_of_bounds.cold+0x44/0x49
snd_emu10k1_playback_hw_params+0x3bc/0x420 [snd_emu10k1]
snd_pcm_hw_params+0x29f/0x600 [snd_pcm]
snd_pcm_common_ioctl+0x188/0x1410 [snd_pcm]
? exit_to_user_mode_prepare+0x35/0x170
? do_syscall_64+0x69/0x90
? syscall_exit_to_user_mode+0x26/0x50
? do_syscall_64+0x69/0x90
? exit_to_user_mode_prepare+0x35/0x170
snd_pcm_ioctl+0x27/0x40 [snd_pcm]
__x64_sys_ioctl+0x95/0xd0
do_syscall_64+0x5c/0x90
? do_syscall_64+0x69/0x90
? do_syscall_64+0x69/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The Linux kernel CVE team has assigned CVE-2022-48702 to this issue.

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

	Fixed in 4.9.328 with commit 637c5310acb4
	Fixed in 4.14.293 with commit 6b0e260ac3cf
	Fixed in 4.19.258 with commit 88aac6684cf8
	Fixed in 5.4.213 with commit 45321a7d02b7
	Fixed in 5.10.143 with commit 39a90720f3ab
	Fixed in 5.15.68 with commit 45814a53514e
	Fixed in 5.19.9 with commit 4204a01ffce9
	Fixed in 6.0 with commit d29f59051d3a

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-2022-48702
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/pci/emu10k1/emupcm.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/637c5310acb48fffcc5657568db3f3e9bc719bfa
	https://git.kernel.org/stable/c/6b0e260ac3cf289e38446552461caa65e6dab275
	https://git.kernel.org/stable/c/88aac6684cf8bc885cca15463cb4407e91f28ff7
	https://git.kernel.org/stable/c/45321a7d02b7cf9b3f97e3987fc1e4d649b82da2
	https://git.kernel.org/stable/c/39a90720f3abe96625d1224e7a7463410875de4c
	https://git.kernel.org/stable/c/45814a53514e10a8014906c882e0d0d38df39cc1
	https://git.kernel.org/stable/c/4204a01ffce97cae1d59edc5848f02be5b2b9178
	https://git.kernel.org/stable/c/d29f59051d3a07b81281b2df2b8c9dfe4716067f