sctp: Call inet6_destroy_sock() via sk->sk_destruct().

After commit d38afeec ("tcp/udp: Call inet6_destroy_sock()
in IPv6 sk->sk_destruct()."), we call inet6_destroy_sock() in
sk->sk_destruct() by setting inet6_sock_destruct() to it to make
sure we do not leak inet6-specific resources.

SCTP sets its own sk->sk_destruct() in the sctp_init_sock(), and
SCTPv6 socket reuses it as the init function.

To call inet6_sock_destruct() from SCTPv6 sk->sk_destruct(), we
set sctp_v6_destruct_sock() in a new init function.
Signed-off-by: NKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/socket.c

@@ -5098,13 +5098,17 @@ static void sctp_destroy_sock(struct sock *sk)
 }
 
 /* Triggered when there are no references on the socket anymore */
-static void sctp_destruct_sock(struct sock *sk)
+static void sctp_destruct_common(struct sock *sk)
 {
 	struct sctp_sock *sp = sctp_sk(sk);
 
 	/* Free up the HMAC transform. */
 	crypto_free_shash(sp->hmac);
+}
 
+static void sctp_destruct_sock(struct sock *sk)
+{
+	sctp_destruct_common(sk);
 	inet_sock_destruct(sk);
 }
 
@@ -9427,7 +9431,7 @@ void sctp_copy_sock(struct sock *newsk, struct sock *sk,
 	sctp_sk(newsk)->reuse = sp->reuse;
 
 	newsk->sk_shutdown = sk->sk_shutdown;
-	newsk->sk_destruct = sctp_destruct_sock;
+	newsk->sk_destruct = sk->sk_destruct;
 	newsk->sk_family = sk->sk_family;
 	newsk->sk_protocol = IPPROTO_SCTP;
 	newsk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
@@ -9662,11 +9666,20 @@ struct proto sctp_prot = {
 
 #if IS_ENABLED(CONFIG_IPV6)
 
-#include <net/transp_v6.h>
-static void sctp_v6_destroy_sock(struct sock *sk)
+static void sctp_v6_destruct_sock(struct sock *sk)
+{
+	sctp_destruct_common(sk);
+	inet6_sock_destruct(sk);
+}
+
+static int sctp_v6_init_sock(struct sock *sk)
 {
-	sctp_destroy_sock(sk);
-	inet6_destroy_sock(sk);
+	int ret = sctp_init_sock(sk);
+
+	if (!ret)
+		sk->sk_destruct = sctp_v6_destruct_sock;
+
+	return ret;
 }
 
 struct proto sctpv6_prot = {
@@ -9676,8 +9689,8 @@ struct proto sctpv6_prot = {
 	.disconnect	= sctp_disconnect,
 	.accept		= sctp_accept,
 	.ioctl		= sctp_ioctl,
-	.init		= sctp_init_sock,
-	.destroy	= sctp_v6_destroy_sock,
+	.init		= sctp_v6_init_sock,
+	.destroy	= sctp_destroy_sock,
 	.shutdown	= sctp_shutdown,
 	.setsockopt	= sctp_setsockopt,
 	.getsockopt	= sctp_getsockopt,