net: mctp: purge receive queues on sk destruction

We may have pending skbs in the receive queue when the sk is being
destroyed; add a destructor to purge the queue.

MCTP doesn't use the error queue, so only the receive_queue is purged.

Fixes: 833ef3b9 ("mctp: Populate socket implementation")
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://lore.kernel.org/r/20230126064551.464468-1-jk@codeconstruct.com.auSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/mctp/af_mctp.c

@@ -587,6 +587,11 @@ static void mctp_sk_unhash(struct sock *sk)
 	del_timer_sync(&msk->key_expiry);
 }
 
+static void mctp_sk_destruct(struct sock *sk)
+{
+	skb_queue_purge(&sk->sk_receive_queue);
+}
+
 static struct proto mctp_proto = {
 	.name		= "MCTP",
 	.owner		= THIS_MODULE,
@@ -623,6 +628,7 @@ static int mctp_pf_create(struct net *net, struct socket *sock,
 		return -ENOMEM;
 
 	sock_init_data(sock, sk);
+	sk->sk_destruct = mctp_sk_destruct;
 
 	rc = 0;
 	if (sk->sk_prot->init)