rxrpc: Fix NULL deref in rxrpc_unuse_local()

Fix rxrpc_unuse_local() to get the debug_id *after* checking to see if
local is NULL.

Fixes: a2cf326 ("rxrpc: Fold __rxrpc_unuse_local() into rxrpc_unuse_local()")
Reported-by: [email protected]
Signed-off-by: David Howells <[email protected]>
Tested-by: [email protected]
cc: Marc Dionne <[email protected]>
cc: [email protected]
Signed-off-by: David S. Miller <[email protected]>

Author: dhowells

net/rxrpc/local_object.c

@@ -357,10 +357,11 @@ struct rxrpc_local *rxrpc_use_local(struct rxrpc_local *local,
  */
 void rxrpc_unuse_local(struct rxrpc_local *local, enum rxrpc_local_trace why)
 {
-	unsigned int debug_id = local->debug_id;
+	unsigned int debug_id;
 	int r, u;
 
 	if (local) {
+		debug_id = local->debug_id;
 		r = refcount_read(&local->ref);
 		u = atomic_dec_return(&local->active_users);
 		trace_rxrpc_local(debug_id, why, r, u);