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e5c0002327
rds_rm_size() handles RDS_CMSG_RDMA_ARGS after only CMSG_OK() and then calls rds_rdma_extra_size(), which reads args->local_vec_addr and args->nr_local without first checking that cmsg_len covers struct rds_rdma_args. The other two RDS_CMSG_RDMA_ARGS consumers already guard this: rds_rdma_bytes() in rds_sendmsg() and rds_cmsg_rdma_args() in rds_cmsg_send() both reject cmsg_len < CMSG_LEN(sizeof(struct rds_rdma_args)). Add the same check to rds_rm_size() so all three RDMA args passes are consistent. This is a consistency and hardening change with no behavioral effect for well-formed senders and no reachable bug today: rds_rdma_bytes() runs before rds_rm_size() in rds_sendmsg() and already rejects a short RDS_CMSG_RDMA_ARGS, so the size pass is not reached with an undersized cmsg. But rds_rm_size() reads the args independently of that earlier pass, and nothing in rds_rm_size() itself records or enforces the precondition, so a reader or a future refactor of the size pass cannot tell the cmsg has already been length-checked. Applying the same cmsg_len guard in all three RDS_CMSG_RDMA_ARGS consumers keeps that invariant local to each and robust to reordering. Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com> Reviewed-by: Allison Henderson <achender@kernel.org> Link: https://patch.msgid.link/20260617023146.2780077-1-michael.bommarito@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>