CVE-2022-21385: 
Linux Kernel vulnerability analysis and mitigation

A flaw in net_rds_alloc_sgs() in Oracle Linux kernels (CVE-2022-21385) allows unprivileged local users to crash the machine. The vulnerability was discovered in 2021 and affects Oracle Linux versions 7, 8, and 9. The issue has a CVSS v3.1 Base Score of 6.2 (Medium) with Availability impacts (NVD, CVE).

The vulnerability exists in the RDS (Reliable Datagram Sockets) subsystem of the Linux kernel where redundant copy_from_user operations in the rds_sendmsg system call expose RDS to an issue where rds_rdma_extra_size walks the RDS iovec and calculates the number of pages (sgs) needed to add to the tail of RDS message. Later, rds_cmsg_rdma_args copies the RDS iovec again and recalculates the same number, potentially getting a different result causing a WARN_ON in rds_message_alloc_sgs (Kernel Commit).

When exploited, this vulnerability can cause a system crash through a kernel panic, affecting system availability. The CVSS scoring indicates no impact on confidentiality or integrity, but a high impact on availability (NVD).

The vulnerability requires local access to the system but does not require privileges or user interaction to exploit. The attack complexity is rated as low, making it relatively straightforward to exploit once local access is obtained (NVD).

The issue has been fixed in the Linux kernel through a patch that modifies the RDS subsystem to perform copy_from_user only once per rds_sendmsg system call. Oracle has released patches for affected Oracle Linux versions (Oracle Bulletin).