ALSA: seq: Do error checks at creating system ports

BugLink: https://bugs.launchpad.net/bugs/1853881

[ Upstream commit b8e13154 ]

snd_seq_system_client_init() doesn't check the errors returned from
its port creations.  Let's do it properly and handle the error paths.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

sound/core/seq/seq_system.c

@@ -123,6 +123,7 @@ int __init snd_seq_system_client_init(void)
 {
 	struct snd_seq_port_callback pcallbacks;
 	struct snd_seq_port_info *port;
+	int err;
 
 	port = kzalloc(sizeof(*port), GFP_KERNEL);
 	if (!port)
@@ -144,7 +145,10 @@ int __init snd_seq_system_client_init(void)
 	port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT;
 	port->addr.client = sysclient;
 	port->addr.port = SNDRV_SEQ_PORT_SYSTEM_TIMER;
-	snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, port);
+	err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT,
+					port);
+	if (err < 0)
+		goto error_port;
 
 	/* register announcement port */
 	strcpy(port->name, "Announce");
@@ -154,16 +158,24 @@ int __init snd_seq_system_client_init(void)
 	port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT;
 	port->addr.client = sysclient;
 	port->addr.port = SNDRV_SEQ_PORT_SYSTEM_ANNOUNCE;
-	snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, port);
+	err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT,
+					port);
+	if (err < 0)
+		goto error_port;
 	announce_port = port->addr.port;
 
 	kfree(port);
 	return 0;
+
+ error_port:
+	snd_seq_system_client_done();
+	kfree(port);
+	return err;
 }
 
 
 /* unregister our internal client */
-void __exit snd_seq_system_client_done(void)
+void snd_seq_system_client_done(void)
 {
 	int oldsysclient = sysclient;