Linux kernel RDS (rds_find_bound socket lookup ignores network namespace): This is a literal cross-tenant delivery bug.

Impact

This is a literal cross-tenant delivery bug. RDS looks sockets up in one global hash table keyed only on address, port and scope - the network namespace is not part of the key - so a sender in namespace A delivers a message to a socket living in namespace B. Container isolation on Linux is network namespaces; a protocol whose demultiplexing ignores them is not isolating anything. The memory-safety consequence follows: the received message points at a connection owned by namespace A, and when that namespace is torn down the connection is freed while the surviving socket in namespace B still references it.

Who can reach it

Local, unprivileged. A tenant creates a network namespace (or is given one, as every container is), binds an RDS socket on an address that collides with another namespace's, and sends.

What to do

Kernel update making namespace part of the RDS bind lookup. Immediate and effective: blacklist the rds and rds_rdma modules. RDS is rarely used outside specific Oracle database deployments and is almost never required on a GPU cluster, so removing it is cheap and needs no reboot.

References