🇰🇷 한글 설명
Linux 커널의 xfrm 서브시스템에서 전송 모드(transport-mode) 패킷을 워크큐를 통해 재주입하도록 수정된 취약점입니다. 기존 구현에서는 IPsec 패킷 처리 중 softirq 컨텍스트가 과도하게 점유되어 CPU soft lockup이 발생할 수 있었습니다.
💡 쉬운 설명
암호화된 네트워크 통신(IPsec) 처리 중 컴퓨터가 특정 작업에 과도하게 묶여 일시적으로 응답하지 않게 되는 문제입니다. 공격자가 이를 악용해 서비스 거부(DoS) 상태를 유발할 수 있습니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
xfrm: Reinject transport-mode packets through workqueue
The following warning is displayed when the tcp6-multi-diffip11 stress
test case of the LTP test suite is tested:
watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [ns-tcpserver:48198]
CPU: 0 PID: 48198 Comm: ns-tcpserver Kdump: loaded Not tainted 6.0.0-rc6+ #39
Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : des3_ede_encrypt+0x27c/0x460 [libdes]
lr : 0x3f
sp : ffff80000ceaa1b0
x29: ffff80000ceaa1b0 x28: ffff0000df056100 x27: ffff0000e51e5280
x26: ffff80004df75030 x25: ffff0000e51e4600 x24: 000000000000003b
x23: 0000000000802080 x22: 000000000000003d x21: 0000000000000038
x20: 0000000080000020 x19: 000000000000000a x18: 0000000000000033
x17: ffff0000e51e4780 x16: ffff80004e2d1448 x15: ffff80004e2d1248
x14: ffff0000e51e4680 x13: ffff80004e2d1348 x12: ffff80004e2d1548
x11: ffff80004e2d1848 x10: ffff80004e2d1648 x9 : ffff80004e2d1748
x8 : ffff80004e2d1948 x7 : 000000000bcaf83d x6 : 000000000000001b
x5 : ffff80004e2d1048 x4 : 00000000761bf3bf x3 : 000000007f1dd0a3
x2 : ffff0000e51e4780 x1 : ffff0000e3b9a2f8 x0 : 00000000db44e872
Call trace:
des3_ede_encrypt+0x27c/0x460 [libdes]
crypto_des3_ede_encrypt+0x1c/0x30 [des_generic]
crypto_cbc_encrypt+0x148/0x190
crypto_skcipher_encrypt+0x2c/0x40
crypto_authenc_encrypt+0xc8/0xfc [authenc]
crypto_aead_encrypt+0x2c/0x40
echainiv_encrypt+0x144/0x1a0 [echainiv]
crypto_aead_encrypt+0x2c/0x40
esp6_output_tail+0x1c8/0x5d0 [esp6]
esp6_output+0x120/0x278 [esp6]
xfrm_output_one+0x458/0x4ec
xfrm_output_resume+0x6c/0x1f0
xfrm_output+0xac/0x4ac
__xfrm6_output+0x130/0x270
xfrm6_output+0x60/0xec
ip6_xmit+0x2ec/0x5bc
inet6_csk_xmit+0xbc/0x10c
__tcp_transmit_skb+0x460/0x8c0
tcp_write_xmit+0x348/0x890
__tcp_push_pending_frames+0x44/0x110
tcp_rcv_established+0x3c8/0x720
tcp_v6_do_rcv+0xdc/0x4a0
tcp_v6_rcv+0xc24/0xcb0
ip6_protocol_deliver_rcu+0xf0/0x574
ip6_input_finish+0x48/0x7c
ip6_input+0x48/0xc0
ip6_rcv_finish+0x80/0x9c
xfrm_trans_reinject+0xb0/0xf4
tasklet_action_common.constprop.0+0xf8/0x134
tasklet_action+0x30/0x3c
__do_softirq+0x128/0x368
do_softirq+0xb4/0xc0
__local_bh_enable_ip+0xb0/0xb4
put_cpu_fpsimd_context+0x40/0x70
kernel_neon_end+0x20/0x40
sha1_base_do_update.constprop.0.isra.0+0x11c/0x140 [sha1_ce]
sha1_ce_finup+0x94/0x110 [sha1_ce]
crypto_shash_finup+0x34/0xc0
hmac_finup+0x48/0xe0
crypto_shash_finup+0x34/0xc0
shash_digest_unaligned+0x74/0x90
crypto_shash_digest+0x4c/0x9c
shash_ahash_digest+0xc8/0xf0
shash_async_digest+0x28/0x34
crypto_ahash_digest+0x48/0xcc
crypto_authenc_genicv+0x88/0xcc [authenc]
crypto_authenc_encrypt+0xd8/0xfc [authenc]
crypto_aead_encrypt+0x2c/0x40
echainiv_encrypt+0x144/0x1a0 [echainiv]
crypto_aead_encrypt+0x2c/0x40
esp6_output_tail+0x1c8/0x5d0 [esp6]
esp6_output+0x120/0x278 [esp6]
xfrm_output_one+0x458/0x4ec
xfrm_output_resume+0x6c/0x1f0
xfrm_output+0xac/0x4ac
__xfrm6_output+0x130/0x270
xfrm6_output+0x60/0xec
ip6_xmit+0x2ec/0x5bc
inet6_csk_xmit+0xbc/0x10c
__tcp_transmit_skb+0x460/0x8c0
tcp_write_xmit+0x348/0x890
__tcp_push_pending_frames+0x44/0x110
tcp_push+0xb4/0x14c
tcp_sendmsg_locked+0x71c/0xb64
tcp_sendmsg+0x40/0x6c
inet6_sendmsg+0x4c/0x80
sock_sendmsg+0x5c/0x6c
__sys_sendto+0x128/0x15c
__arm64_sys_sendto+0x30/0x40
invoke_syscall+0x50/0x120
el0_svc_common.constprop.0+0x170/0x194
do_el0_svc+0x38/0x4c
el0_svc+0x28/0xe0
el0t_64_sync_handler+0xbc/0x13c
el0t_64_sync+0x180/0x184
Get softirq info by bcc tool:
./softirqs -NT 10
Tracing soft irq event time... Hit Ctrl-C to end.
15:34:34
SOFTIRQ TOTAL_nsecs
block 158990
timer 20030920
sched 46577080
net_rx 676746820
tasklet 9906067650
15:34:45
SOFTIRQ TOTAL_nsecs
block 86100
sched 38849790
net_rx
---truncated---
📍 영향받는 시스템
패치 이전의 Linux 커널 (IPsec xfrm 전송 모드를 사용하는 시스템, 6.0 계열 등)
⚔️ 공격 벡터
IPsec 전송 모드 트래픽을 대량으로 유발하여 커널의 softirq 처리를 장시간 점유시키는 방식의 서비스 거부
🛡️ 대응 방법
배포판 커널을 CVE-2022-50445 수정이 포함된 최신 안정 버전으로 업데이트하고 재부팅합니다.
🔧 검증 코드
출력된 커널 버전을 배포판의 보안 권고문에서 CVE-2022-50445 수정 포함 버전과 비교하여 패치 여부를 확인합니다.