🇰🇷 한글 설명
Linux 커널의 Bluetooth MGMT 모듈에서 광고 모니터링 추가 실패 시 메모리 해제 및 관리 과정에서 발생하는 Use-After-Free 취약점입니다. MSFT 오프로드 설정 단계에서 오류가 발생할 경우, 이미 해제된 메모리 영역에 접근을 시도하여 시스템 불안정이나 커널 패닉을 유발할 수 있습니다.
💡 쉬운 설명
블루투스 기능을 사용할 때 특정 설정 과정에서 오류가 나면, 컴퓨터가 이미 지워버린 메모리 정보를 다시 읽으려고 시도하는 버그입니다. 이로 인해 시스템이 갑자기 멈추거나 보안 문제가 생길 수 있습니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: MGMT: Fix adv monitor add failure cleanup
hci_add_adv_monitor() publishes a new adv_monitor in
hdev->adv_monitors_idr before the powered MSFT setup step. The MSFT
offload add path can then fail either locally before the controller add
command completes, or in the MSFT add callback. In the current queued
management add flow, hci_cmd_sync_work() still invokes
mgmt_add_adv_patterns_monitor_complete() with the original pending command
after msft_add_monitor_pattern() returns.
The buggy scenario involves two paths, with each column showing the order
within that path:
MSFT add handling MGMT completion
1. insert monitor and handle 1. receive sync error
2. send MSFT add command 2. call add-monitor completion
3. callback sees bad response 3. load cmd->user_data
4. callback frees monitor 4. read monitor->handle
Local MSFT setup failures have the other half of the same ownership bug:
they return an error after the IDR insertion, but no later code removes the
failed monitor from the IDR.
Keep ownership with the pending management command until its completion.
For normal management adds, the MSFT add callback now records successful
controller state and returns errors to its caller. The management
completion frees the monitor on non-success after copying the response
handle, while resume/reregister callback-error cleanup remains in the
MSFT callback. The success path keeps the existing bookkeeping.
Validation reproduced this kernel report:
BUG: KASAN: slab-use-after-free in mgmt_add_adv_patterns_monitor_complete+0xfb/0x260 [bluetooth]
Call Trace:
<TASK>
dump_stack_lvl+0x66/0xa0
print_report+0xce/0x5f0
? mgmt_add_adv_patterns_monitor_complete+0xfb/0x260 [bluetooth]
? srso_alias_return_thunk+0x5/0xfbef5
? __virt_addr_valid+0x19f/0x330
? mgmt_add_adv_patterns_monitor_complete+0xfb/0x260 [bluetooth]
kasan_report+0xe0/0x110
? mgmt_add_adv_patterns_monitor_complete+0xfb/0x260 [bluetooth]
mgmt_add_adv_patterns_monitor_complete+0xfb/0x260 [bluetooth]
? srso_alias_return_thunk+0x5/0xfbef5
? 0xffffffffc00d00da
? __pfx_mgmt_add_adv_patterns_monitor_complete+0x10/0x10 [bluetooth]
? __pfx_mgmt_add_adv_patterns_monitor_complete+0x10/0x10 [bluetooth]
? hci_cmd_sync_work+0x1ab/0x210 [bluetooth]
hci_cmd_sync_work+0x1c0/0x210 [bluetooth]
? __pfx_mgmt_add_adv_patterns_monitor_complete+0x10/0x10 [bluetooth]
process_one_work+0x4fd/0xbc0
? __pfx_process_one_work+0x10/0x10
? srso_alias_return_thunk+0x5/0xfbef5
? srso_alias_return_thunk+0x5/0xfbef5
? __list_add_valid_or_report+0x37/0xf0
? __pfx_hci_cmd_sync_work+0x10/0x10 [bluetooth]
? srso_alias_return_thunk+0x5/0xfbef5
worker_thread+0x2d8/0x570
? __pfx_worker_thread+0x10/0x10
kthread+0x1ad/0x1f0
? __pfx_kthread+0x10/0x10
ret_from_fork+0x3c9/0x540
? __pfx_ret_from_fork+0x10/0x10
? srso_alias_return_thunk+0x5/0xfbef5
? __switch_to+0x2e9/0x730
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Allocated by task 471 on cpu 3 at 285.205389s:
kasan_save_stack+0x33/0x60
kasan_save_track+0x17/0x60
__kasan_kmalloc+0xaa/0xb0
add_adv_patterns_monitor_rssi+0xd5/0x230 [bluetooth]
hci_sock_sendmsg+0x96b/0xf80 [bluetooth]
__sys_sendto+0x2bc/0x2d0
__x64_sys_sendto+0x76/0x90
do_syscall_64+0x115/0x6a0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 454 on cpu 2 at 285.217112s:
kasan_save_stack+0x33/0x60
kasan_save_track+0x17/0x60
kasan_save_free_info+0x3b/0x60
__kasan_slab_free+0x5f/0x80
kfree+0x313/0x590
msft_add_monitor_sync+0x54a/0x570 [bluetooth]
hci_add_adv_monitor+0x133/0x180 [bluetooth]
hci_cmd_sync_work+0x187/0x210 [bluetooth]
process_one_work+0x4fd/0xbc0
worker_thread+0x2d8/0x570
kthread+0x1ad/0x1f0
ret_from_fork+0x3c9/0x540
ret_from_fork_asm+0x1a/0x30
📍 영향받는 시스템
Linux Kernel (Bluetooth subsystem using MSFT offload)
⚔️ 공격 벡터
로컬 공격자가 블루투스 관리 명령(mgmt_add_adv_patterns_monitor)을 조작하여 메모리 오류 유도
🛡️ 대응 방법
Linux 커널을 최신 보안 패치가 적용된 버전으로 업데이트하십시오.
🔧 검증 코드
출력된 커널 버전이 해당 취약점이 해결된 패치 버전 이후인지 확인하십시오.
📊 CVSS Vector String
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
💻 영향받는 소프트웨어
Cisco Integrated Management Controller