sctp: fix /proc/net/sctp/ memory leak

Commit 13d782f6 ("sctp: Make the proc files per network namespace.")
changed the /proc/net/sctp/ struct file_operations opener functions to
use single_open_net() and seq_open_net().

Avoid leaking memory by using single_release_net() and seq_release_net()
as the release functions.

Discovered with Trinity (the syscall fuzzer).
Signed-off-by: NTommi Rantala <tt.rantala@gmail.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/proc.c

@@ -102,7 +102,7 @@ static const struct file_operations sctp_snmp_seq_fops = {
 	.open	 = sctp_snmp_seq_open,
 	.read	 = seq_read,
 	.llseek	 = seq_lseek,
-	.release = single_release,
+	.release = single_release_net,
 };
 
 /* Set up the proc fs entry for 'snmp' object. */
@@ -251,7 +251,7 @@ static const struct file_operations sctp_eps_seq_fops = {
 	.open	 = sctp_eps_seq_open,
 	.read	 = seq_read,
 	.llseek	 = seq_lseek,
-	.release = seq_release,
+	.release = seq_release_net,
 };
 
 /* Set up the proc fs entry for 'eps' object. */
@@ -372,7 +372,7 @@ static const struct file_operations sctp_assocs_seq_fops = {
 	.open	 = sctp_assocs_seq_open,
 	.read	 = seq_read,
 	.llseek	 = seq_lseek,
-	.release = seq_release,
+	.release = seq_release_net,
 };
 
 /* Set up the proc fs entry for 'assocs' object. */
@@ -517,7 +517,7 @@ static const struct file_operations sctp_remaddr_seq_fops = {
 	.open = sctp_remaddr_seq_open,
 	.read = seq_read,
 	.llseek = seq_lseek,
-	.release = seq_release,
+	.release = seq_release_net,
 };
 
 int __net_init sctp_remaddr_proc_init(struct net *net)