CVE-2026-98257rds: ib: use rds_conn_drop() on protocol version mismatch

Official description

In the Linux kernel, the following vulnerability has been resolved: rds: ib: use rds_conn_drop() on protocol version mismatch rds_ib_cm_connect_complete() runs from the RDMA-CM event handler with conn->c_cm_lock held. When the peer negotiates a protocol version older than RDS_PROTOCOL_COMPAT_VERSION, the handler calls rds_conn_destroy(), which is only safe in the rmmod path: it synchronously tears the connection down and flush_work()es the shutdown work cp_down_w. That shutdown work (rds_conn_shutdown()) needs cp_cm_lock, which is the very lock the event handler still holds, so the flush never completes: the two workers wait on each other and the RDS connection workqueues stall for good. All other RDMA-CM failure paths (REJECTED, CONNECT_ERROR, DISCONNECTED) use rds_conn_drop(), which marks the connection RDS_CONN_ERROR and schedules the shutdown work asynchronously. Use it here as well.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/424019be3f637da76b74f44a40034669acbb166f
• https://git.kernel.org/stable/c/14fb90067d13f4494cff0f03243fae3cf2911cbc
• https://git.kernel.org/stable/c/344c72a0bc2703a6de4918ed935850e07dae3af2
• https://git.kernel.org/stable/c/b5c9f2951d330d4a198a64d6e60f79b4bd6ef078
• https://git.kernel.org/stable/c/d392b16acd0908f077289aad8bba066ff16de336
• https://git.kernel.org/stable/c/65ca0a5037152a5a80b8fe6aac80eb80458be573
• https://git.kernel.org/stable/c/7d8c22cb2cb1efb5e830a4545c76abf7b35cc2e8
• https://git.kernel.org/stable/c/f97d8c7bab7843631206a114986c9059da03efeb