rxrpc: Fix potential infinite loop in rxrpc_recvmsg()

commit 67a0332 upstream.

Fix the wait in rxrpc_recvmsg() also take check the oob queue.

Fixes: 5800b1c ("rxrpc: Allow CHALLENGEs to the passed to the app for a RESPONSE")
Link: https://sashiko.dev/#/patchset/20260616155749.2125907-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: stable@kernel.org
Link: https://patch.msgid.link/20260624163819.3017002-9-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: dhowells

net/rxrpc/recvmsg.c

@@ -436,7 +436,8 @@ int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 		return -EAGAIN;
 	}
 
-	if (list_empty(&rx->recvmsg_q)) {
+	if (list_empty(&rx->recvmsg_q) &&
+	    skb_queue_empty_lockless(&rx->recvmsg_oobq)) {
 		ret = -EWOULDBLOCK;
 		if (timeo == 0) {
 			call = NULL;