CVE-2022-48702

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