When sctp_stream_outq_migrate() is called to release stream out resources,
the memory pointed to by prio_head in stream out is not released.

The memory leak information is as follows:
unreferenced object 0xffff88801fe79f80 (size 64):
  comm "sctp_repo", pid 7957, jiffies 4294951704 (age 36.480s)
  hex dump (first 32 bytes):
    80 9f e7 1f 80 88 ff ff 80 9f e7 1f 80 88 ff ff  ................
    90 9f e7 1f 80 88 ff ff 90 9f e7 1f 80 88 ff ff  ................
  backtrace:
    [<ffffffff81b215c6>] kmalloc_trace+0x26/0x60
    [<ffffffff88ae517c>] sctp_sched_prio_set+0x4cc/0x770
    [<ffffffff88ad64f2>] sctp_stream_init_ext+0xd2/0x1b0
    [<ffffffff88aa2604>] sctp_sendmsg_to_asoc+0x1614/0x1a30
    [<ffffffff88ab7ff1>] sctp_sendmsg+0xda1/0x1ef0
    [<ffffffff87f765ed>] inet_sendmsg+0x9d/0xe0
    [<ffffffff8754b5b3>] sock_sendmsg+0xd3/0x120
    [<ffffffff8755446a>] __sys_sendto+0x23a/0x340
    [<ffffffff87554651>] __x64_sys_sendto+0xe1/0x1b0
    [<ffffffff89978b49>] do_syscall_64+0x39/0xb0
    [<ffffffff89a0008b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: 637784ade221 ("sctp: introduce priority based stream scheduler")
Reported-by: syzbot+29c402e56c4760763cc0@syzkaller.appspotmail.com
Signed-off-by: Zhengchao Shao <redacted>
---
 net/sctp/stream.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/sctp/stream.c b/net/sctp/stream.c
index ef9fceadef8d..a17dc368876f 100644
--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c

@@ -70,6 +70,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream,
 		 * sctp_stream_update will swap ->out pointers.
 		 */
 		for (i = 0; i < outcnt; i++) {
+			if (SCTP_SO(new, i)->ext)
+				kfree(SCTP_SO(new, i)->ext->prio_head);
+
 			kfree(SCTP_SO(new, i)->ext);
 			SCTP_SO(new, i)->ext = SCTP_SO(stream, i)->ext;
 			SCTP_SO(stream, i)->ext = NULL;

@@ -77,6 +80,9 @@ static void sctp_stream_outq_migrate(struct sctp_stream *stream,
 	}
 
 	for (i = outcnt; i < stream->outcnt; i++) {
+		if (SCTP_SO(stream, i)->ext)
+			kfree(SCTP_SO(stream, i)->ext->prio_head);
+
 		kfree(SCTP_SO(stream, i)->ext);
 		SCTP_SO(stream, i)->ext = NULL;
 	}

-- 
2.17.1