🇰🇷 한글 설명
Linux 커널의 ionic 네트워크 드라이버에서 netif_napi_del() 함수가 poll 포인터를 NULL로 초기화하지 않아 발생하는 사용 후 해제(use-after-free) 취약점입니다. 큐 재설정 시 이미 제거된 NAPI 인터페이스에 대해 napi_enable()이 호출되어 커널 패닉을 유발합니다.
💡 쉬운 설명
Linux kernel's ionic network driver incorrectly tries to enable network queues that have already been deleted, causing the system to crash. This happens when you change the network queue configuration using the ethtool command.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
ionic: fix use after netif_napi_del()
When queues are started, netif_napi_add() and napi_enable() are called.
If there are 4 queues and only 3 queues are used for the current
configuration, only 3 queues' napi should be registered and enabled.
The ionic_qcq_enable() checks whether the .poll pointer is not NULL for
enabling only the using queue' napi. Unused queues' napi will not be
registered by netif_napi_add(), so the .poll pointer indicates NULL.
But it couldn't distinguish whether the napi was unregistered or not
because netif_napi_del() doesn't reset the .poll pointer to NULL.
So, ionic_qcq_enable() calls napi_enable() for the queue, which was
unregistered by netif_napi_del().
Reproducer:
ethtool -L <interface name> rx 1 tx 1 combined 0
ethtool -L <interface name> rx 0 tx 0 combined 1
ethtool -L <interface name> rx 0 tx 0 combined 4
Splat looks like:
kernel BUG at net/core/dev.c:6666!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
CPU: 3 PID: 1057 Comm: kworker/3:3 Not tainted 6.10.0-rc2+ #16
Workqueue: events ionic_lif_deferred_work [ionic]
RIP: 0010:napi_enable+0x3b/0x40
Code: 48 89 c2 48 83 e2 f6 80 b9 61 09 00 00 00 74 0d 48 83 bf 60 01 00 00 00 74 03 80 ce 01 f0 4f
RSP: 0018:ffffb6ed83227d48 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff97560cda0828 RCX: 0000000000000029
RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff97560cda0a28
RBP: ffffb6ed83227d50 R08: 0000000000000400 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: ffff97560ce3c1a0 R14: 0000000000000000 R15: ffff975613ba0a20
FS: 0000000000000000(0000) GS:ffff975d5f780000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8f734ee200 CR3: 0000000103e50000 CR4: 00000000007506f0
PKRU: 55555554
Call Trace:
<TASK>
? die+0x33/0x90
? do_trap+0xd9/0x100
? napi_enable+0x3b/0x40
? do_error_trap+0x83/0xb0
? napi_enable+0x3b/0x40
? napi_enable+0x3b/0x40
? exc_invalid_op+0x4e/0x70
? napi_enable+0x3b/0x40
? asm_exc_invalid_op+0x16/0x20
? napi_enable+0x3b/0x40
ionic_qcq_enable+0xb7/0x180 [ionic 59bdfc8a035436e1c4224ff7d10789e3f14643f8]
ionic_start_queues+0xc4/0x290 [ionic 59bdfc8a035436e1c4224ff7d10789e3f14643f8]
ionic_link_status_check+0x11c/0x170 [ionic 59bdfc8a035436e1c4224ff7d10789e3f14643f8]
ionic_lif_deferred_work+0x129/0x280 [ionic 59bdfc8a035436e1c4224ff7d10789e3f14643f8]
process_one_work+0x145/0x360
worker_thread+0x2bb/0x3d0
? __pfx_worker_thread+0x10/0x10
kthread+0xcc/0x100
? __pfx_kthread+0x10/0x10
ret_from_fork+0x2d/0x50
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
📍 영향받는 시스템
Linux kernel 6.10-rc2 and earlier versions with ionic network driver; systems with Ionic NICs
⚔️ 공격 벡터
Local privilege escalation via ethtool commands to reconfigure network queues (requires root/CAP_NET_ADMIN)
🛡️ 대응 방법
Update Linux kernel to patched version (6.10-rc3 or later, or backported fixes to stable kernels)
🔧 검증 코드
첫 번째 명령은 ionic 드라이버 로드 여부 확인, 두 번째는 취약한 커널 버전 확인입니다. 둘 다 결과가 나오면 취약점 대상입니다.
grep -i ionic /proc/modules && uname -r | grep -E '^6\.(1[0-9]|[0-9])\.0-rc[1-2]'