🇰🇷 한글 설명
Linux 커널의 ACPICA 구성요소에서 조기 중단(early abort) 상황 시 Acpi-Parse 및 Acpi-parse_ext 슬랩 캐시가 해제되지 않아 메모리 누수가 발생하는 문제입니다. 캐시 객체 크기가 같아 Acpi-State 캐시와 병합되었고, SLAB_NEVER_MERGE 플래그 사용으로 실제 누수 지점이 확인되었습니다. 이 문제는 커널 부팅 과정의 메모리 관리 결함으로 보고되었습니다.
💡 쉬운 설명
컴퓨터의 하드웨어 설정 관리 기능에서 시작 실패 시 일부 메모리가 반환되지 않고 남는 버그입니다. 주로 메모리 낭비와 시스템 안정성 저하로 이어질 수 있습니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
ACPICA: fix acpi parse and parseext cache leaks
ACPICA commit 8829e70e1360c81e7a5a901b5d4f48330e021ea5
I'm Seunghun Han, and I work for National Security Research Institute of
South Korea.
I have been doing a research on ACPI and found an ACPI cache leak in ACPI
early abort cases.
Boot log of ACPI cache leak is as follows:
[ 0.352414] ACPI: Added _OSI(Module Device)
[ 0.353182] ACPI: Added _OSI(Processor Device)
[ 0.353182] ACPI: Added _OSI(3.0 _SCP Extensions)
[ 0.353182] ACPI: Added _OSI(Processor Aggregator Device)
[ 0.356028] ACPI: Unable to start the ACPI Interpreter
[ 0.356799] ACPI Error: Could not remove SCI handler (20170303/evmisc-281)
[ 0.360215] kmem_cache_destroy Acpi-State: Slab cache still has objects
[ 0.360648] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W
4.12.0-rc4-next-20170608+ #10
[ 0.361273] Hardware name: innotek gmb_h virtual_box/virtual_box, BIOS
virtual_box 12/01/2006
[ 0.361873] Call Trace:
[ 0.362243] ? dump_stack+0x5c/0x81
[ 0.362591] ? kmem_cache_destroy+0x1aa/0x1c0
[ 0.362944] ? acpi_sleep_proc_init+0x27/0x27
[ 0.363296] ? acpi_os_delete_cache+0xa/0x10
[ 0.363646] ? acpi_ut_delete_caches+0x6d/0x7b
[ 0.364000] ? acpi_terminate+0xa/0x14
[ 0.364000] ? acpi_init+0x2af/0x34f
[ 0.364000] ? __class_create+0x4c/0x80
[ 0.364000] ? video_setup+0x7f/0x7f
[ 0.364000] ? acpi_sleep_proc_init+0x27/0x27
[ 0.364000] ? do_one_initcall+0x4e/0x1a0
[ 0.364000] ? kernel_init_freeable+0x189/0x20a
[ 0.364000] ? rest_init+0xc0/0xc0
[ 0.364000] ? kernel_init+0xa/0x100
[ 0.364000] ? ret_from_fork+0x25/0x30
I analyzed this memory leak in detail. I found that “Acpi-State” cache and
“Acpi-Parse” cache were merged because the size of cache objects was same
slab cache size.
I finally found “Acpi-Parse” cache and “Acpi-parse_ext” cache were leaked
using SLAB_NEVER_MERGE flag in kmem_cache_create() function.
Real ACPI cache leak point is as follows:
[ 0.360101] ACPI: Added _OSI(Module Device)
[ 0.360101] ACPI: Added _OSI(Processor Device)
[ 0.360101] ACPI: Added _OSI(3.0 _SCP Extensions)
[ 0.361043] ACPI: Added _OSI(Processor Aggregator Device)
[ 0.364016] ACPI: Unable to start the ACPI Interpreter
[ 0.365061] ACPI Error: Could not remove SCI handler (20170303/evmisc-281)
[ 0.368174] kmem_cache_destroy Acpi-Parse: Slab cache still has objects
[ 0.369332] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W
4.12.0-rc4-next-20170608+ #8
[ 0.371256] Hardware name: innotek gmb_h virtual_box/virtual_box, BIOS
virtual_box 12/01/2006
[ 0.372000] Call Trace:
[ 0.372000] ? dump_stack+0x5c/0x81
[ 0.372000] ? kmem_cache_destroy+0x1aa/0x1c0
[ 0.372000] ? acpi_sleep_proc_init+0x27/0x27
[ 0.372000] ? acpi_os_delete_cache+0xa/0x10
[ 0.372000] ? acpi_ut_delete_caches+0x56/0x7b
[ 0.372000] ? acpi_terminate+0xa/0x14
[ 0.372000] ? acpi_init+0x2af/0x34f
[ 0.372000] ? __class_create+0x4c/0x80
[ 0.372000] ? video_setup+0x7f/0x7f
[ 0.372000] ? acpi_sleep_proc_init+0x27/0x27
[ 0.372000] ? do_one_initcall+0x4e/0x1a0
[ 0.372000] ? kernel_init_freeable+0x189/0x20a
[ 0.372000] ? rest_init+0xc0/0xc0
[ 0.372000] ? kernel_init+0xa/0x100
[ 0.372000] ? ret_from_fork+0x25/0x30
[ 0.388039] kmem_cache_destroy Acpi-parse_ext: Slab cache still has objects
[ 0.389063] CPU: 1 PID: 1 Comm: swapper/0 Tainted: G W
4.12.0-rc4-next-20170608+ #8
[ 0.390557] Hardware name: innotek gmb_h virtual_box/virtual_box, BIOS
virtual_box 12/01/2006
[ 0.392000] Call Trace:
[ 0.392000] ? dump_stack+0x5c/0x81
[ 0.392000] ? kmem_cache_destroy+0x1aa/0x1c0
[ 0.392000] ? acpi_sleep_proc_init+0x27/0x27
[ 0.392000] ? acpi_os_delete_cache+0xa/0x10
[ 0.392000] ? acpi_ut_delete_caches+0x6d/0x7b
[ 0.392000] ? acpi_terminate+0xa/0x14
[ 0.392000] ? acpi_init+0x2af/0x3
---truncated---
📍 영향받는 시스템
ACPICA 코드를 포함한 Linux 커널 (수정 커밋 적용 이전 버전)
⚔️ 공격 벡터
로컬 공격자가 직접 악용하기는 어렵고, 주로 ACPI 초기화 실패 상황에서 발생하는 커널 메모리 누수 결함입니다.
🛡️ 대응 방법
배포판 제공 최신 커널로 업데이트하여 ACPICA 수정 커밋(8829e70e1360c81e7a5a901b5d4f48330e021ea5)이 포함된 버전을 설치하세요.
🔧 검증 코드
출력된 커널 버전을 배포판 보안 공지와 대조해 해당 수정이 포함된 빌드인지 확인하세요 (수정 커밋이 적용된 최신 안정 버전인지 비교).