🇰🇷 한글 설명
Linux 커널의 mt7601u Wi-Fi 드라이버에서 정수 언더플로우 취약점이 발견되었습니다. 공격자가 URB 패킷의 dma_len 값을 조작하면 seg_len에서 언더플로우가 발생하며, 이로 인해 잘못된 포인터 참조(Null Pointer Dereference)가 발생하여 시스템이 충돌할 수 있습니다.
💡 쉬운 설명
Wi-Fi 장치로 들어오는 데이터의 길이를 계산하는 과정에서 숫자가 너무 작아져 오류가 발생하는 문제입니다. 이 오류를 이용하면 컴퓨터 시스템을 강제로 멈추게 하거나 충돌을 일으킬 수 있습니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
wifi: mt7601u: fix an integer underflow
Fix an integer underflow that leads to a null pointer dereference in
'mt7601u_rx_skb_from_seg()'. The variable 'dma_len' in the URB packet
could be manipulated, which could trigger an integer underflow of
'seg_len' in 'mt7601u_rx_process_seg()'. This underflow subsequently
causes the 'bad_frame' checks in 'mt7601u_rx_skb_from_seg()' to be
bypassed, eventually leading to a dereference of the pointer 'p', which
is a null pointer.
Ensure that 'dma_len' is greater than 'min_seg_len'.
Found by a modified version of syzkaller.
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 PID: 12 Comm: ksoftirqd/0 Tainted: G W O 5.14.0+
#139
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
RIP: 0010:skb_add_rx_frag+0x143/0x370
Code: e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 86 01 00 00 4c 8d 7d 08 44
89 68 08 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 <80> 3c 02
00 0f 85 cd 01 00 00 48 8b 45 08 a8 01 0f 85 3d 01 00 00
RSP: 0018:ffffc900000cfc90 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888115520dc0 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffff8881118430c0 RDI: ffff8881118430f8
RBP: 0000000000000000 R08: 0000000000000e09 R09: 0000000000000010
R10: ffff888111843017 R11: ffffed1022308602 R12: 0000000000000000
R13: 0000000000000e09 R14: 0000000000000010 R15: 0000000000000008
FS: 0000000000000000(0000) GS:ffff88811a800000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000004035af40 CR3: 00000001157f2000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
mt7601u_rx_tasklet+0xc73/0x1270
? mt7601u_submit_rx_buf.isra.0+0x510/0x510
? tasklet_action_common.isra.0+0x79/0x2f0
tasklet_action_common.isra.0+0x206/0x2f0
__do_softirq+0x1b5/0x880
? tasklet_unlock+0x30/0x30
run_ksoftirqd+0x26/0x50
smpboot_thread_fn+0x34f/0x7d0
? smpboot_register_percpu_thread+0x370/0x370
kthread+0x3a1/0x480
? set_kthread_struct+0x120/0x120
ret_from_fork+0x1f/0x30
Modules linked in: 88XXau(O) 88x2bu(O)
---[ end trace 57f34f93b4da0f9b ]---
RIP: 0010:skb_add_rx_frag+0x143/0x370
Code: e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 86 01 00 00 4c 8d 7d 08 44
89 68 08 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 <80> 3c 02
00 0f 85 cd 01 00 00 48 8b 45 08 a8 01 0f 85 3d 01 00 00
RSP: 0018:ffffc900000cfc90 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888115520dc0 RCX: 0000000000000000
RDX: 0000000000000001 RSI: ffff8881118430c0 RDI: ffff8881118430f8
RBP: 0000000000000000 R08: 0000000000000e09 R09: 0000000000000010
R10: ffff888111843017 R11: ffffed1022308602 R12: 0000000000000000
R13: 0000000000000e09 R14: 0000000000000010 R15: 0000000000000008
FS: 0000000000000000(0000) GS:ffff88811a800000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000004035af40 CR3: 00000001157f2000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
📍 영향받는 시스템
Linux kernel (mt7601u driver component)
⚔️ 공격 벡터
조작된 URB 패킷을 전송하여 Wi-Fi 드라이버의 정수 계산 오류 유도
🛡️ 대응 방법
Linux 커널을 최신 보안 패치가 적용된 버전으로 업데이트하십시오.
🔧 검증 코드
출력된 커널 버전이 해당 취약점이 수정된 패치 버전 이후인지 확인하십시오.