🇰🇷 한글 설명
Linux 커널 IPv6 라우팅 함수 rt6_probe()에서 NULL 포인터 역참조 취약점. __in6_dev_get() 함수가 NULL을 반환할 때 적절한 검사가 없어 발생하며, IPv6 패킷 처리 중 커널 Oops를 유발합니다.
💡 쉬운 설명
Linux 커널이 IPv6 네트워크 요청 처리 중 메모리 주소를 제대로 확인하지 않아 시스템이 충돌할 수 있습니다. 로컬 공격자가 특수한 IPv6 패킷을 보내 시스템을 다운시킬 수 있습니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
ipv6: prevent possible NULL dereference in rt6_probe()
syzbot caught a NULL dereference in rt6_probe() [1]
Bail out if __in6_dev_get() returns NULL.
[1]
Oops: general protection fault, probably for non-canonical address 0xdffffc00000000cb: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000658-0x000000000000065f]
CPU: 1 PID: 22444 Comm: syz-executor.0 Not tainted 6.10.0-rc2-syzkaller-00383-gb8481381d4e2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:rt6_probe net/ipv6/route.c:656 [inline]
RIP: 0010:find_match+0x8c4/0xf50 net/ipv6/route.c:758
Code: 14 fd f7 48 8b 85 38 ff ff ff 48 c7 45 b0 00 00 00 00 48 8d b8 5c 06 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 19
RSP: 0018:ffffc900034af070 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90004521000
RDX: 00000000000000cb RSI: ffffffff8990d0cd RDI: 000000000000065c
RBP: ffffc900034af150 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000002 R12: 000000000000000a
R13: 1ffff92000695e18 R14: ffff8880244a1d20 R15: 0000000000000000
FS: 00007f4844a5a6c0(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31b27000 CR3: 000000002d42c000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
rt6_nh_find_match+0xfa/0x1a0 net/ipv6/route.c:784
nexthop_for_each_fib6_nh+0x26d/0x4a0 net/ipv4/nexthop.c:1496
__find_rr_leaf+0x6e7/0xe00 net/ipv6/route.c:825
find_rr_leaf net/ipv6/route.c:853 [inline]
rt6_select net/ipv6/route.c:897 [inline]
fib6_table_lookup+0x57e/0xa30 net/ipv6/route.c:2195
ip6_pol_route+0x1cd/0x1150 net/ipv6/route.c:2231
pol_lookup_func include/net/ip6_fib.h:616 [inline]
fib6_rule_lookup+0x386/0x720 net/ipv6/fib6_rules.c:121
ip6_route_output_flags_noref net/ipv6/route.c:2639 [inline]
ip6_route_output_flags+0x1d0/0x640 net/ipv6/route.c:2651
ip6_dst_lookup_tail.constprop.0+0x961/0x1760 net/ipv6/ip6_output.c:1147
ip6_dst_lookup_flow+0x99/0x1d0 net/ipv6/ip6_output.c:1250
rawv6_sendmsg+0xdab/0x4340 net/ipv6/raw.c:898
inet_sendmsg+0x119/0x140 net/ipv4/af_inet.c:853
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
sock_write_iter+0x4b8/0x5c0 net/socket.c:1160
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0x6b6/0x1140 fs/read_write.c:590
ksys_write+0x1f8/0x260 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
📍 영향받는 시스템
Linux kernel 6.10.0-rc2 및 이전 버전 (IPv6 라우팅 기능이 활성화된 시스템)
⚔️ 공격 벡터
로컬에서 특수한 IPv6 네트워크 요청(raw socket, sendmsg)을 통해 rt6_probe() 함수의 NULL 포인터 역참조 유발
🛡️ 대응 방법
Linux 커널을 6.10.0-rc3 이상 또는 해당 CVE 패치가 적용된 버전으로 업그레이드
🔧 검증 코드
커널 버전 확인 후 6.10.0-rc2 이하이면 취약할 수 있음. 정확한 판단을 위해서는 /boot/config 또는 커널 소스에서 rt6_probe() 함수의 패치 적용 여부 직접 확인 필요
uname -r | grep -E '^6\.(10\.[0-2]|[0-9]\.|[0-8]\.)' && echo 'Potentially vulnerable' || echo 'Check manually'