🇰🇷 한글 설명
Linux 커널 RDS(Reliable Datagram Sockets) 모듈의 __rds_rdma_map 함수에서 null 포인터 참조 취약점이 존재합니다. NULL일 수 있는 cp 매개변수를 사전 검사 없이 사용하여 시스템 크래시 및 거부 서비스 공격을 유발할 수 있습니다.
💡 쉬운 설명
Linux kernel's network code fails to check if a connection pointer is empty before using it, which can crash the system. A local attacker can exploit RDS socket operations to trigger this vulnerability.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
net/rds: fix possible cp null dereference
cp might be null, calling cp->cp_conn would produce null dereference
[Simon Horman adds:]
Analysis:
* cp is a parameter of __rds_rdma_map and is not reassigned.
* The following call-sites pass a NULL cp argument to __rds_rdma_map()
- rds_get_mr()
- rds_get_mr_for_dest
* Prior to the code above, the following assumes that cp may be NULL
(which is indicative, but could itself be unnecessary)
trans_private = rs->rs_transport->get_mr(
sg, nents, rs, &mr->r_key, cp ? cp->cp_conn : NULL,
args->vec.addr, args->vec.bytes,
need_odp ? ODP_ZEROBASED : ODP_NOT_NEEDED);
* The code modified by this patch is guarded by IS_ERR(trans_private),
where trans_private is assigned as per the previous point in this analysis.
The only implementation of get_mr that I could locate is rds_ib_get_mr()
which can return an ERR_PTR if the conn (4th) argument is NULL.
* ret is set to PTR_ERR(trans_private).
rds_ib_get_mr can return ERR_PTR(-ENODEV) if the conn (4th) argument is NULL.
Thus ret may be -ENODEV in which case the code in question will execute.
Conclusion:
* cp may be NULL at the point where this patch adds a check;
this patch does seem to address a possible bug
📍 영향받는 시스템
Linux kernel with RDS module enabled (unpatched versions before mid-2024)
⚔️ 공격 벡터
Local attacker triggers null pointer dereference through RDS RDMA operations via rds_get_mr() or rds_get_mr_for_dest() function calls
🛡️ 대응 방법
Update Linux kernel to patched version (2024 or later) that includes null pointer check in __rds_rdma_map function
🔧 검증 코드
Compare installed kernel version against CVE-2024-35902 patch date; kernel versions released before mid-2024 are potentially vulnerable
dpkg -l 2>/dev/null | grep linux-image | awk '{print $2,$3}' | head -1