[PATCH net v1] sctp: Unwind address notifier registration on failure

[Yuho Choi <dbgh9129@gmail.com>]

sctp_v4_add_protocol() and sctp_v6_add_protocol() register their
address notifiers before registering the SCTP protocol handlers. If
protocol registration fails, the functions return without unregistering
the notifiers.

Unregister the notifiers on the protocol registration failure paths.
Also propagate notifier registration failures instead of ignoring them.

Fixes: 827bf12236fb ("[SCTP]: Re-order SCTP initializations to avoid race with sctp_rcv()")
Fixes: 270637abff0c ("[SCTP]: Fix a race between module load and protosw access")
Signed-off-by: Yuho Choi <dbgh9129@gmail.com>
---
 net/sctp/ipv6.c     | 10 ++++++++--
 net/sctp/protocol.c | 10 ++++++++--
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index cd15b695607e..ef26878f1282 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -1176,11 +1176,17 @@ void sctp_v6_protosw_exit(void)
 /* Register with inet6 layer. */
 int sctp_v6_add_protocol(void)
 {
+	int ret;
+
 	/* Register notifier for inet6 address additions/deletions. */
-	register_inet6addr_notifier(&sctp_inet6addr_notifier);
+	ret = register_inet6addr_notifier(&sctp_inet6addr_notifier);
+	if (ret)
+		return ret;
 
-	if (inet6_add_protocol(&sctpv6_protocol, IPPROTO_SCTP) < 0)
+	if (inet6_add_protocol(&sctpv6_protocol, IPPROTO_SCTP) < 0) {
+		unregister_inet6addr_notifier(&sctp_inet6addr_notifier);
 		return -EAGAIN;
+	}
 
 	return 0;
 }
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 5800e7ee7ea0..6153340f1b45 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -1263,12 +1263,18 @@ static void sctp_v4_protosw_exit(void)
 
 static int sctp_v4_add_protocol(void)
 {
+	int ret;
+
 	/* Register notifier for inet address additions/deletions. */
-	register_inetaddr_notifier(&sctp_inetaddr_notifier);
+	ret = register_inetaddr_notifier(&sctp_inetaddr_notifier);
+	if (ret)
+		return ret;
 
 	/* Register SCTP with inet layer.  */
-	if (inet_add_protocol(&sctp_protocol, IPPROTO_SCTP) < 0)
+	if (inet_add_protocol(&sctp_protocol, IPPROTO_SCTP) < 0) {
+		unregister_inetaddr_notifier(&sctp_inetaddr_notifier);
 		return -EAGAIN;
+	}
 
 	return 0;
 }
-- 
2.43.0