CVE-2026-97476

In the Linux kernel, the following vulnerability has been resolved:

rds: filter RDS_INFO_* getsockopt by caller's netns

The RDS_INFO_* family of getsockopt(2) options reads several

file-scope global lists that are not per-netns:

rds_sock_info / rds6_sock_info,

rds_sock_inc_info / rds6_sock_inc_info -> rds_sock_list

rds_tcp_tc_info / rds6_tcp_tc_info -> rds_tcp_tc_list

rds_conn_info / rds6_conn_info,

rds_conn_message_info_cmn (for the *_SEND_MESSAGES and

*_RETRANS_MESSAGES variants),

rds_for_each_conn_info (for RDS_INFO_IB_CONNECTIONS)

-> rds_conn_hash[]

The handlers do not filter by the caller's network namespace.

rds_info_getsockopt() has no netns or capable() check, and

rds_create() has no capable() check, so AF_RDS is reachable from

an unprivileged user namespace. As a result, an unprivileged

caller in a fresh user_ns plus netns can read the bound address

and sock inode of every RDS socket on the host, the peer address

of incoming messages on every RDS socket on the host, the peer

address and TCP sequence numbers of every rds-tcp connection on

the host, and the peer address and RDS sequence numbers of every

RDS connection on the host.

The rds-tcp transport is reachable from a non-initial netns (see

rds_set_transport()), so a one-shot init_net gate at

rds_info_getsockopt() would deny legitimate per-netns visibility

to rds-tcp callers. Instead, filter at each handler by comparing

the netns of the caller's socket to the netns of the list entry,

or to rds_conn_net(conn) for connection paths. Only copy entries

whose netns matches the caller. Counters (RDS_INFO_COUNTERS) are

aggregate statistics and remain global.

Reproducer (KASAN VM, rds and rds_tcp loaded): an AF_RDS socket

binds 127.0.0.1:4242 in init_net as root. A child process enters

a fresh user_ns plus netns and opens AF_RDS there, then calls

getsockopt(SOL_RDS, RDS_INFO_SOCKETS). Before this change, the

child sees the init_net socket. After this change, the child

sees zero entries.

Drop the rds_sock_count, rds_tcp_tc_count, and rds6_tcp_tc_count

globals. v2 used them for the size precheck and lens->nr; v3

replaced the precheck with a per-ns count from a first pass over

the list, so the globals have no remaining readers. The matching

increments and decrements in rds_create()/rds_destroy_sock() and

rds_tcp_set_callbacks()/rds_tcp_restore_callbacks() go away with

them. Reported by the kernel test robot under clang W=1.