🇰🇷 한글 설명
Linux 커널의 ath10k 드라이버에서 펌웨어 복구 중 시스템이 즉시 절전 모드로 진입할 때 발생하는 Double Free 취약점입니다. 펌웨어 복구 프로세스와 절전 모드 중지 프로세스가 동시에 실행되면서 동일한 메모리 영역을 두 번 해제하여 커널 크래시를 유발합니다.
💡 쉬운 설명
무선 랜 카드가 오류를 고치려고 재시작하는 도중에 컴퓨터가 잠자기 모드로 들어가면, 메모리를 중복으로 삭제하려다 시스템이 멈추는 문제입니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
ath10k: skip ath10k_halt during suspend for driver state RESTARTING
Double free crash is observed when FW recovery(caused by wmi
timeout/crash) is followed by immediate suspend event. The FW recovery
is triggered by ath10k_core_restart() which calls driver clean up via
ath10k_halt(). When the suspend event occurs between the FW recovery,
the restart worker thread is put into frozen state until suspend completes.
The suspend event triggers ath10k_stop() which again triggers ath10k_halt()
The double invocation of ath10k_halt() causes ath10k_htt_rx_free() to be
called twice(Note: ath10k_htt_rx_alloc was not called by restart worker
thread because of its frozen state), causing the crash.
To fix this, during the suspend flow, skip call to ath10k_halt() in
ath10k_stop() when the current driver state is ATH10K_STATE_RESTARTING.
Also, for driver state ATH10K_STATE_RESTARTING, call
ath10k_wait_for_suspend() in ath10k_stop(). This is because call to
ath10k_wait_for_suspend() is skipped later in
[ath10k_halt() > ath10k_core_stop()] for the driver state
ATH10K_STATE_RESTARTING.
The frozen restart worker thread will be cancelled during resume when the
device comes out of suspend.
Below is the crash stack for reference:
[ 428.469167] ------------[ cut here ]------------
[ 428.469180] kernel BUG at mm/slub.c:4150!
[ 428.469193] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
[ 428.469219] Workqueue: events_unbound async_run_entry_fn
[ 428.469230] RIP: 0010:kfree+0x319/0x31b
[ 428.469241] RSP: 0018:ffffa1fac015fc30 EFLAGS: 00010246
[ 428.469247] RAX: ffffedb10419d108 RBX: ffff8c05262b0000
[ 428.469252] RDX: ffff8c04a8c07000 RSI: 0000000000000000
[ 428.469256] RBP: ffffa1fac015fc78 R08: 0000000000000000
[ 428.469276] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 428.469285] Call Trace:
[ 428.469295] ? dma_free_attrs+0x5f/0x7d
[ 428.469320] ath10k_core_stop+0x5b/0x6f
[ 428.469336] ath10k_halt+0x126/0x177
[ 428.469352] ath10k_stop+0x41/0x7e
[ 428.469387] drv_stop+0x88/0x10e
[ 428.469410] __ieee80211_suspend+0x297/0x411
[ 428.469441] rdev_suspend+0x6e/0xd0
[ 428.469462] wiphy_suspend+0xb1/0x105
[ 428.469483] ? name_show+0x2d/0x2d
[ 428.469490] dpm_run_callback+0x8c/0x126
[ 428.469511] ? name_show+0x2d/0x2d
[ 428.469517] __device_suspend+0x2e7/0x41b
[ 428.469523] async_suspend+0x1f/0x93
[ 428.469529] async_run_entry_fn+0x3d/0xd1
[ 428.469535] process_one_work+0x1b1/0x329
[ 428.469541] worker_thread+0x213/0x372
[ 428.469547] kthread+0x150/0x15f
[ 428.469552] ? pr_cont_work+0x58/0x58
[ 428.469558] ? kthread_blkcg+0x31/0x31
Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00288-QCARMSWPZ-1
📍 영향받는 시스템
Linux kernel (ath10k driver, specifically QCA6174 hardware environments)
⚔️ 공격 벡터
펌웨어 오류(WMI 타임아웃 등)를 유도한 직후 시스템을 절전 모드로 전환하여 발생
🛡️ 대응 방법
Linux 커널을 최신 보안 패치가 적용된 버전으로 업데이트하여 ath10k_halt 중복 호출 방지 로직 적용
🔧 검증 코드
출력된 커널 버전을 확인하여 해당 취약점이 수정된 패치 버전 이상인지 확인합니다.