🇰🇷 한글 설명
Linux 커널의 mlx5e 드라이버에서 프로파일 변경 롤백이 실패했을 때, 넷디바이스의 priv 구조체가 초기화된 상태로 남아 이후 재시도 시 NULL 포인터 역참조로 커널 크래시가 발생하는 문제입니다. 수정으로 이전 실패 상태의 빈 priv를 안전하게 처리하도록 개선되었습니다.
💡 쉬운 설명
Mellanox 네트워크 카드를 가상 스위치 모드로 바꾸다가 실패한 뒤 다시 시도하면 시스템이 갑자기 멈출 수 있습니다. 이 문제는 로컬 관리 작업 중에만 발생하며 보안 패치로 해결됩니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Fix crash on profile change rollback failure
mlx5e_netdev_change_profile can fail to attach a new profile and can
fail to rollback to old profile, in such case, we could end up with a
dangling netdev with a fully reset netdev_priv. A retry to change
profile, e.g. another attempt to call mlx5e_netdev_change_profile via
switchdev mode change, will crash trying to access the now NULL
priv->mdev.
This fix allows mlx5e_netdev_change_profile() to handle previous
failures and an empty priv, by not assuming priv is valid.
Pass netdev and mdev to all flows requiring
mlx5e_netdev_change_profile() and avoid passing priv.
In mlx5e_netdev_change_profile() check if current priv is valid, and if
not, just attach the new profile without trying to access the old one.
This fixes the following oops, when enabling switchdev mode for the 2nd
time after first time failure:
## Enabling switchdev mode first time:
mlx5_core 0012:03:00.1: E-Switch: Supported tc chains and prios offload
workqueue: Failed to create a rescuer kthread for wq "mlx5e": -EINTR
mlx5_core 0012:03:00.1: mlx5e_netdev_init_profile:6214:(pid 37199): mlx5e_priv_init failed, err=-12
mlx5_core 0012:03:00.1 gpu3rdma1: mlx5e_netdev_change_profile: new profile init failed, -12
workqueue: Failed to create a rescuer kthread for wq "mlx5e": -EINTR
mlx5_core 0012:03:00.1: mlx5e_netdev_init_profile:6214:(pid 37199): mlx5e_priv_init failed, err=-12
mlx5_core 0012:03:00.1 gpu3rdma1: mlx5e_netdev_change_profile: failed to rollback to orig profile, -12
^^^^^^^^
mlx5_core 0000:00:03.0: E-Switch: Disable: mode(LEGACY), nvfs(0), necvfs(0), active vports(0)
## retry: Enabling switchdev mode 2nd time:
mlx5_core 0000:00:03.0: E-Switch: Supported tc chains and prios offload
BUG: kernel NULL pointer dereference, address: 0000000000000038
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP NOPTI
CPU: 13 UID: 0 PID: 520 Comm: devlink Not tainted 6.18.0-rc4+ #91 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014
RIP: 0010:mlx5e_detach_netdev+0x3c/0x90
Code: 50 00 00 f0 80 4f 78 02 48 8b bf e8 07 00 00 48 85 ff 74 16 48 8b 73 78 48 d1 ee 83 e6 01 83 f6 01 40 0f b6 f6 e8 c4 42 00 00 <48> 8b 45 38 48 85 c0 74 08 48 89 df e8 cc 47 40 1e 48 8b bb f0 07
RSP: 0018:ffffc90000673890 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8881036a89c0 RCX: 0000000000000000
RDX: ffff888113f63800 RSI: ffffffff822fe720 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000002dcd R09: 0000000000000000
R10: ffffc900006738e8 R11: 00000000ffffffff R12: 0000000000000000
R13: 0000000000000000 R14: ffff8881036a89c0 R15: 0000000000000000
FS: 00007fdfb8384740(0000) GS:ffff88856a9d6000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000038 CR3: 0000000112ae0005 CR4: 0000000000370ef0
Call Trace:
<TASK>
mlx5e_netdev_change_profile+0x45/0xb0
mlx5e_vport_rep_load+0x27b/0x2d0
mlx5_esw_offloads_rep_load+0x72/0xf0
esw_offloads_enable+0x5d0/0x970
mlx5_eswitch_enable_locked+0x349/0x430
? is_mp_supported+0x57/0xb0
mlx5_devlink_eswitch_mode_set+0x26b/0x430
devlink_nl_eswitch_set_doit+0x6f/0xf0
genl_family_rcv_msg_doit+0xe8/0x140
genl_rcv_msg+0x18b/0x290
? __pfx_devlink_nl_pre_doit+0x10/0x10
? __pfx_devlink_nl_eswitch_set_doit+0x10/0x10
? __pfx_devlink_nl_post_doit+0x10/0x10
? __pfx_genl_rcv_msg+0x10/0x10
netlink_rcv_skb+0x52/0x100
genl_rcv+0x28/0x40
netlink_unicast+0x282/0x3e0
? __alloc_skb+0xd6/0x190
netlink_sendmsg+0x1f7/0x430
__sys_sendto+0x213/0x220
? __sys_recvmsg+0x6a/0xd0
__x64_sys_sendto+0x24/0x30
do_syscall_64+0x50/0x1f0
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fdfb8495047
📍 영향받는 시스템
Linux 커널 6.18-rc4 이전의 mlx5e 드라이버를 사용하는 Mellanox ConnectX 기반 시스템
⚔️ 공격 벡터
로컬 권한을 가진 사용자가 devlink로 switchdev 모드 변경을 반복 시도하여 커널 패닉(서비스 거부)을 유발
🛡️ 대응 방법
커널을 해당 CVE 수정이 포함된 최신 안정 버전으로 업데이트하고 재부팅
🔧 검증 코드
커널 버전이 CVE 수정이 포함된 최신 패치 버전 이상인지 배포판 보안 공지와 대조하고, mlx5_core가 로드되지 않았다면 이 취약점은 해당되지 않습니다.
uname -r && (lsmod | grep mlx5_core || echo 'mlx5_core not loaded')