🇰🇷 한글 설명
Linux 커널의 mlxsw 드라이버에서 rehash 작업 중 오류가 발생할 경우, 청크 마커는 초기화되지만 엔트리 마커는 초기화되지 않는 결함이 있습니다. 이로 인해 잘못된 위치에서 마이그레이션이 재개되어 데이터 구조를 잘못 참조하게 되며, 시스템 경고를 발생시킵니다.
💡 쉬운 설명
데이터를 옮기는 작업 중에 문제가 생기면 기록해둔 위치 정보가 꼬이게 됩니다. 이로 인해 컴퓨터가 엉뚱한 데이터를 읽으려 시도하면서 시스템에 경고 메시지를 띄우게 됩니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
mlxsw: spectrum_acl_tcam: Fix warning during rehash
As previously explained, the rehash delayed work migrates filters from
one region to another. This is done by iterating over all chunks (all
the filters with the same priority) in the region and in each chunk
iterating over all the filters.
When the work runs out of credits it stores the current chunk and entry
as markers in the per-work context so that it would know where to resume
the migration from the next time the work is scheduled.
Upon error, the chunk marker is reset to NULL, but without resetting the
entry markers despite being relative to it. This can result in migration
being resumed from an entry that does not belong to the chunk being
migrated. In turn, this will eventually lead to a chunk being iterated
over as if it is an entry. Because of how the two structures happen to
be defined, this does not lead to KASAN splats, but to warnings such as
[1].
Fix by creating a helper that resets all the markers and call it from
all the places the currently only reset the chunk marker. For good
measures also call it when starting a completely new rehash. Add a
warning to avoid future cases.
[1]
WARNING: CPU: 7 PID: 1076 at drivers/net/ethernet/mellanox/mlxsw/core_acl_flex_keys.c:407 mlxsw_afk_encode+0x242/0x2f0
Modules linked in:
CPU: 7 PID: 1076 Comm: kworker/7:24 Tainted: G W 6.9.0-rc3-custom-00880-g29e61d91b77b #29
Hardware name: Mellanox Technologies Ltd. MSN3700/VMOD0005, BIOS 5.11 01/06/2019
Workqueue: mlxsw_core mlxsw_sp_acl_tcam_vregion_rehash_work
RIP: 0010:mlxsw_afk_encode+0x242/0x2f0
[...]
Call Trace:
<TASK>
mlxsw_sp_acl_atcam_entry_add+0xd9/0x3c0
mlxsw_sp_acl_tcam_entry_create+0x5e/0xa0
mlxsw_sp_acl_tcam_vchunk_migrate_all+0x109/0x290
mlxsw_sp_acl_tcam_vregion_rehash_work+0x6c/0x470
process_one_work+0x151/0x370
worker_thread+0x2cb/0x3e0
kthread+0xd0/0x100
ret_from_fork+0x34/0x50
</TASK>
📍 영향받는 시스템
Linux kernel (mlxsw driver 사용 시스템)
⚔️ 공격 벡터
로컬 공격자가 네트워크 필터링 설정을 조작하여 재해시(rehash) 프로세스를 유도함으로써 경고를 발생시키거나 시스템 불안정을 유도할 수 있음
🛡️ 대응 방법
Linux 커널을 최신 보안 패치가 적용된 버전으로 업데이트하십시오.
🔧 검증 코드
출력된 커널 버전이 해당 취약점이 수정된 패치 버전 이후인지 확인하십시오.