🇰🇷 한글 설명
Linux 커널의 ASoC qcom: q6apm 드라이버에서 컴포넌트 등록 시 관리형(managed) API를 사용하여 발생하는 Use-After-Free 취약점입니다. 잘못된 해제 순서로 인해 컴포넌트가 참조 중인 DAI(Digital Audio Interface)가 먼저 해제되어 커널 메모리 오류를 유발합니다.
💡 쉬운 설명
오디오 장치를 관리하는 프로그램이 장치를 정리하는 순서를 잘못 계산하여, 이미 사라진 부품을 다시 사용하려고 시도하는 오류입니다. 이로 인해 시스템이 불안정해지거나 갑자기 멈출 수 있습니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
ASoC: qcom: q6apm: move component registration to unmanaged version
q6apm component registers dais dynamically from ASoC toplology, which
are allocated using device managed version apis. Allocating both
component and dynamic dais using managed version could lead to incorrect
free ordering, dai will be freed while component still holding references
to it.
Fix this issue by moving component to unmanged version so
that the dai pointers are only freeded after the component is removed.
==================================================================
BUG: KASAN: slab-use-after-free in snd_soc_del_component_unlocked+0x3d4/0x400 [snd_soc_core]
Read of size 8 at addr ffff00084493a6e8 by task kworker/u48:0/3426
Tainted: [W]=WARN
Hardware name: LENOVO 21N2ZC5PUS/21N2ZC5PUS, BIOS N42ET57W (1.31 ) 08/08/2024
Workqueue: pdr_notifier_wq pdr_notifier_work [pdr_interface]
Call trace:
show_stack+0x28/0x7c (C)
dump_stack_lvl+0x60/0x80
print_report+0x160/0x4b4
kasan_report+0xac/0xfc
__asan_report_load8_noabort+0x20/0x34
snd_soc_del_component_unlocked+0x3d4/0x400 [snd_soc_core]
snd_soc_unregister_component_by_driver+0x50/0x88 [snd_soc_core]
devm_component_release+0x30/0x5c [snd_soc_core]
devres_release_all+0x13c/0x210
device_unbind_cleanup+0x20/0x190
device_release_driver_internal+0x350/0x468
device_release_driver+0x18/0x30
bus_remove_device+0x1a0/0x35c
device_del+0x314/0x7f0
device_unregister+0x20/0xbc
apr_remove_device+0x5c/0x7c [apr]
device_for_each_child+0xd8/0x160
apr_pd_status+0x7c/0xa8 [apr]
pdr_notifier_work+0x114/0x240 [pdr_interface]
process_one_work+0x500/0xb70
worker_thread+0x630/0xfb0
kthread+0x370/0x6c0
ret_from_fork+0x10/0x20
Allocated by task 77:
kasan_save_stack+0x40/0x68
kasan_save_track+0x20/0x40
kasan_save_alloc_info+0x44/0x58
__kasan_kmalloc+0xbc/0xdc
__kmalloc_node_track_caller_noprof+0x1f4/0x620
devm_kmalloc+0x7c/0x1c8
snd_soc_register_dai+0x50/0x4f0 [snd_soc_core]
soc_tplg_pcm_elems_load+0x55c/0x1eb8 [snd_soc_core]
snd_soc_tplg_component_load+0x4f8/0xb60 [snd_soc_core]
audioreach_tplg_init+0x124/0x1fc [snd_q6apm]
q6apm_audio_probe+0x10/0x1c [snd_q6apm]
snd_soc_component_probe+0x5c/0x118 [snd_soc_core]
soc_probe_component+0x44c/0xaf0 [snd_soc_core]
snd_soc_bind_card+0xad0/0x2370 [snd_soc_core]
snd_soc_register_card+0x3b0/0x4c0 [snd_soc_core]
devm_snd_soc_register_card+0x50/0xc8 [snd_soc_core]
x1e80100_platform_probe+0x208/0x368 [snd_soc_x1e80100]
platform_probe+0xc0/0x188
really_probe+0x188/0x804
__driver_probe_device+0x158/0x358
driver_probe_device+0x60/0x190
__device_attach_driver+0x16c/0x2a8
bus_for_each_drv+0x100/0x194
__device_attach+0x174/0x380
device_initial_probe+0x14/0x20
bus_probe_device+0x124/0x154
deferred_probe_work_func+0x140/0x220
process_one_work+0x500/0xb70
worker_thread+0x630/0xfb0
kthread+0x370/0x6c0
ret_from_fork+0x10/0x20
Freed by task 3426:
kasan_save_stack+0x40/0x68
kasan_save_track+0x20/0x40
__kasan_save_free_info+0x4c/0x80
__kasan_slab_free+0x78/0xa0
kfree+0x100/0x4a4
devres_release_all+0x144/0x210
device_unbind_cleanup+0x20/0x190
device_release_driver_internal+0x350/0x468
device_release_driver+0x18/0x30
bus_remove_device+0x1a0/0x35c
device_del+0x314/0x7f0
device_unregister+0x20/0xbc
apr_remove_device+0x5c/0x7c [apr]
device_for_each_child+0xd8/0x160
apr_pd_status+0x7c/0xa8 [apr]
pdr_notifier_work+0x114/0x240 [pdr_interface]
process_one_work+0x500/0xb70
worker_thread+0x630/0xfb0
kthread+0x370/0x6c0
ret_from_fork+0x10/0x20
📍 영향받는 시스템
Linux kernel (ASoC qcom: q6apm driver components)
⚔️ 공격 벡터
로컬 공격자가 특정 오디오 장치 구성이나 드라이버 언바인딩을 유도하여 커널 메모리 오류를 발생시킬 수 있음
🛡️ 대응 방법
컴포넌트 등록 방식을 관리형(managed)에서 비관리형(unmanaged)으로 변경하여 DAI 해제 순서를 보장하는 커널 패치 적용
🔧 검증 코드
커널 버전을 확인하고 dmesg 로그에서 해당 함수와 관련된 KASAN Use-After-Free 오류 메시지가 있는지 확인합니다.
uname -r && dmesg | grep -i 'snd_soc_del_component_unlocked'