rxrpc: Fix return from none_validate_challenge()

Fix the return value of none_validate_challenge() to be explicitly true
(which indicates the source packet should simply be discarded) rather than
implicitly true (because rxrpc_abort_conn() always returns -EPROTO which
gets converted to true).

Note that this change doesn't change the behaviour of the code (which is
correct by accident) and, in any case, we *shouldn't* get a CHALLENGE
packet to an rxnull connection (ie. no security).

Reported-by: Dan Carpenter <[email protected]>
Closes: https://lists.infradead.org/pipermail/linux-afs/2025-April/009738.html
Signed-off-by: David Howells <[email protected]>
cc: Marc Dionne <[email protected]>
cc: Jakub Kicinski <[email protected]>
cc: "David S. Miller" <[email protected]>
cc: Eric Dumazet <[email protected]>
cc: Paolo Abeni <[email protected]>
cc: Simon Horman <[email protected]>
cc: [email protected]
cc: [email protected]
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Fixes: 5800b1c ("rxrpc: Allow CHALLENGEs to the passed to the app for a RESPONSE")
Signed-off-by: Paolo Abeni <[email protected]>

Author: dhowells

net/rxrpc/insecure.c

@@ -45,8 +45,9 @@ static void none_free_call_crypto(struct rxrpc_call *call)
 static bool none_validate_challenge(struct rxrpc_connection *conn,
 				    struct sk_buff *skb)
 {
-	return rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO,
-				rxrpc_eproto_rxnull_challenge);
+	rxrpc_abort_conn(conn, skb, RX_PROTOCOL_ERROR, -EPROTO,
+			 rxrpc_eproto_rxnull_challenge);
+	return true;
 }
 
 static int none_sendmsg_respond_to_challenge(struct sk_buff *challenge,