CVE-2022-48702

/// Technical 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 D

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References