🇰🇷 한글 설명
리눅스 커널의 블루투스 스택에서 HCI_EV_NUM_COMP_PKTS 이벤트를 처리할 때 hdev에 대한 잠금(locking)이 적절히 이루어지지 않아 발생하는 Use-After-Free(UAF) 취약점입니다. 이로 인해 이미 해제된 메모리 영역에 접근하게 되어 시스템 불안정이나 권한 상승이 발생할 수 있습니다.
💡 쉬운 설명
블루투스 통신 과정에서 데이터가 처리되는 순서가 꼬여, 이미 삭제된 메모리 정보를 다시 사용하려고 시도하는 오류입니다. 이 문제가 발생하면 컴퓨터가 갑자기 멈추거나 해커가 시스템 제어권을 얻을 위험이 있습니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_event: Fix UAF in hci_conn_tx_dequeue
This fixes the following UAF caused by not properly locking hdev when
processing HCI_EV_NUM_COMP_PKTS:
BUG: KASAN: slab-use-after-free in hci_conn_tx_dequeue+0x1be/0x220 net/bluetooth/hci_conn.c:3036
Read of size 4 at addr ffff8880740f0940 by task kworker/u11:0/54
CPU: 1 UID: 0 PID: 54 Comm: kworker/u11:0 Not tainted 6.16.0-rc7 #3 PREEMPT(full)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
Workqueue: hci1 hci_rx_work
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x230 mm/kasan/report.c:480
kasan_report+0x118/0x150 mm/kasan/report.c:593
hci_conn_tx_dequeue+0x1be/0x220 net/bluetooth/hci_conn.c:3036
hci_num_comp_pkts_evt+0x1c8/0xa50 net/bluetooth/hci_event.c:4404
hci_event_func net/bluetooth/hci_event.c:7477 [inline]
hci_event_packet+0x7e0/0x1200 net/bluetooth/hci_event.c:7531
hci_rx_work+0x46a/0xe80 net/bluetooth/hci_core.c:4070
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
kthread+0x70e/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 home/kwqcheii/source/fuzzing/kernel/kasan/linux-6.16-rc7/arch/x86/entry/entry_64.S:245
</TASK>
Allocated by task 54:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
kasan_kmalloc include/linux/kasan.h:260 [inline]
__kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4359
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
__hci_conn_add+0x233/0x1b30 net/bluetooth/hci_conn.c:939
le_conn_complete_evt+0x3d6/0x1220 net/bluetooth/hci_event.c:5628
hci_le_enh_conn_complete_evt+0x189/0x470 net/bluetooth/hci_event.c:5794
hci_event_func net/bluetooth/hci_event.c:7474 [inline]
hci_event_packet+0x78c/0x1200 net/bluetooth/hci_event.c:7531
hci_rx_work+0x46a/0xe80 net/bluetooth/hci_core.c:4070
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
kthread+0x70e/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 home/kwqcheii/source/fuzzing/kernel/kasan/linux-6.16-rc7/arch/x86/entry/entry_64.S:245
Freed by task 9572:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2381 [inline]
slab_free mm/slub.c:4643 [inline]
kfree+0x18e/0x440 mm/slub.c:4842
device_release+0x9c/0x1c0
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x22b/0x480 lib/kobject.c:737
hci_conn_cleanup net/bluetooth/hci_conn.c:175 [inline]
hci_conn_del+0x8ff/0xcb0 net/bluetooth/hci_conn.c:1173
hci_abort_conn_sync+0x5d1/0xdf0 net/bluetooth/hci_sync.c:5689
hci_cmd_sync_work+0x210/0x3a0 net/bluetooth/hci_sync.c:332
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
kthread+0x70e/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 home/kwqcheii/source/fuzzing/kernel/kasan/linux-6.16-rc7/arch/x86/entry/entry_64.S:245
📍 영향받는 시스템
Linux kernel (specifically versions including 6.16.0-rc7 and related Bluetooth stack components)
⚔️ 공격 벡터
특수하게 조작된 블루투스 HCI 이벤트를 전송하여 메모리 해제 후 재사용을 유도하는 방식
🛡️ 대응 방법
리눅스 커널을 최신 보안 패치가 적용된 버전으로 업데이트하여 hci_conn_tx_dequeue 함수의 잠금 메커니즘을 수정해야 합니다.
🔧 검증 코드
출력된 커널 버전이 취약점이 수정된 최신 패치 버전인지 확인합니다.