CVE-2026-31638

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

rxrpc: Only put the call ref if one was acquired

rxrpcinputpacketonconn() can process a to-client packet after the current client call on the channel has already been torn down. In that case chan->call is NULL, rxrpctryget_call() returns NULL and there is no reference to drop.

The client-side implicit-end error path does not account for that and unconditionally calls rxrpcputcall(). This turns a protocol error path into a kernel crash instead of rejecting the packet.

Only drop the call reference if one was actually acquired. Keep the existing protocol error handling unchanged.