🇰🇷 한글 설명
Linux 커널의 mlx5e 드라이버에서 flow post action 속성을 중복으로 복제하면서 발생하는 Use-After-Free 취약점입니다. 이로 인해 속성이 제대로 업데이트되지 않아 메모리 관리 오류가 발생하며 시스템 불안정성을 초래할 수 있습니다.
💡 쉬운 설명
데이터를 복사하는 과정에서 실수로 똑같은 작업을 두 번 수행하여, 이미 사용 중이거나 삭제된 메모리 영역에 접근하게 되는 오류입니다. 이 오류는 컴퓨터 시스템을 멈추게 하거나 보안 문제를 일으킬 수 있습니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Don't clone flow post action attributes second time
The code already clones post action attributes in
mlx5e_clone_flow_attr_for_post_act(). Creating another copy in
mlx5e_tc_post_act_add() is a erroneous leftover from original
implementation. Instead, assign handle->attribute to post_attr provided by
the caller. Note that cloning the attribute second time is not just
wasteful but also causes issues like second copy not being properly updated
in neigh update code which leads to following use-after-free:
Feb 21 09:02:00 c-237-177-40-045 kernel: BUG: KASAN: use-after-free in mlx5_cmd_set_fte+0x200d/0x24c0 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: kasan_report+0xbb/0x1a0
Feb 21 09:02:00 c-237-177-40-045 kernel: kasan_save_stack+0x1e/0x40
Feb 21 09:02:00 c-237-177-40-045 kernel: kasan_set_track+0x21/0x30
Feb 21 09:02:00 c-237-177-40-045 kernel: __kasan_kmalloc+0x7a/0x90
Feb 21 09:02:00 c-237-177-40-045 kernel: kasan_save_stack+0x1e/0x40
Feb 21 09:02:00 c-237-177-40-045 kernel: kasan_set_track+0x21/0x30
Feb 21 09:02:00 c-237-177-40-045 kernel: kasan_save_free_info+0x2a/0x40
Feb 21 09:02:00 c-237-177-40-045 kernel: ____kasan_slab_free+0x11a/0x1b0
Feb 21 09:02:00 c-237-177-40-045 kernel: page dumped because: kasan: bad access detected
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5_core 0000:08:00.0: mlx5_cmd_out_err:803:(pid 8833): SET_FLOW_TABLE_ENTRY(0x936) op_mod(0x0) failed, status bad resource state(0x9), syndrome (0xf2ff71), err(-22)
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5_core 0000:08:00.0 enp8s0f0: Failed to add post action rule
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5_core 0000:08:00.0: mlx5e_tc_encap_flows_add:190:(pid 8833): Failed to update flow post acts, -22
Feb 21 09:02:00 c-237-177-40-045 kernel: Call Trace:
Feb 21 09:02:00 c-237-177-40-045 kernel: <TASK>
Feb 21 09:02:00 c-237-177-40-045 kernel: dump_stack_lvl+0x57/0x7d
Feb 21 09:02:00 c-237-177-40-045 kernel: print_report+0x170/0x471
Feb 21 09:02:00 c-237-177-40-045 kernel: ? mlx5_cmd_set_fte+0x200d/0x24c0 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: kasan_report+0xbb/0x1a0
Feb 21 09:02:00 c-237-177-40-045 kernel: ? mlx5_cmd_set_fte+0x200d/0x24c0 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5_cmd_set_fte+0x200d/0x24c0 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: ? __module_address.part.0+0x62/0x200
Feb 21 09:02:00 c-237-177-40-045 kernel: ? mlx5_cmd_stub_create_flow_table+0xd0/0xd0 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: ? __raw_spin_lock_init+0x3b/0x110
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5_cmd_create_fte+0x80/0xb0 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: add_rule_fg+0xe80/0x19c0 [mlx5_core]
--
Feb 21 09:02:00 c-237-177-40-045 kernel: Allocated by task 13476:
Feb 21 09:02:00 c-237-177-40-045 kernel: kasan_save_stack+0x1e/0x40
Feb 21 09:02:00 c-237-177-40-045 kernel: kasan_set_track+0x21/0x30
Feb 21 09:02:00 c-237-177-40-045 kernel: __kasan_kmalloc+0x7a/0x90
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5_packet_reformat_alloc+0x7b/0x230 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5e_tc_tun_create_header_ipv4+0x977/0xf10 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5e_attach_encap+0x15b4/0x1e10 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: post_process_attr+0x305/0xa30 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5e_tc_add_fdb_flow+0x4c0/0xcf0 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: __mlx5e_add_fdb_flow+0x7cf/0xe90 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5e_configure_flower+0xcaa/0x4b90 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5e_rep_setup_tc_cls_flower+0x99/0x1b0 [mlx5_core]
Feb 21 09:02:00 c-237-177-40-045 kernel: mlx5e_rep_setup_tc_cb+0x133/0x1e0 [mlx5_core]
--
Feb 21 09:02:00 c-237-177-40-045 kernel: Freed by task 8833:
Feb 21 09:02:00 c-237-177-40-045 kernel: kasan_save_s
---truncated---
📍 영향받는 시스템
Linux kernel (mlx5e driver components)
⚔️ 공격 벡터
로컬 공격자가 네트워크 트래픽 제어를 위한 특수하게 조작된 flow rule을 추가하여 메모리 오류를 유도할 수 있음
🛡️ 대응 방법
Linux 커널을 최신 보안 패치가 적용된 버전으로 업데이트하십시오.
🔧 검증 코드
출력된 커널 버전이 해당 취약점이 해결된 패치 버전 이후인지 확인하십시오.