[PATCH 5.15.y] ALSA: wavefront: Clear substream pointers on close

[Sasha Levin <sashal@kernel.org>]

From: Junrui Luo <moonafterrain@outlook.com>

[ Upstream commit e11c5c13ce0ab2325d38fe63500be1dd88b81e38 ]

Clear substream pointers in close functions to avoid leaving dangling
pointers, helping to improve code safety and
prevents potential issues.

Reported-by: Yuhao Jiang <danisjiang@gmail.com>
Reported-by: Junrui Luo <moonafterrain@outlook.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Junrui Luo <moonafterrain@outlook.com>
Link: https://patch.msgid.link/SYBPR01MB7881DF762CAB45EE42F6D812AFC2A@SYBPR01MB7881.ausprd01.prod.outlook.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
[ No guard() in older trees ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/isa/wavefront/wavefront_midi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/isa/wavefront/wavefront_midi.c b/sound/isa/wavefront/wavefront_midi.c
index 72e775ac7ad7f..a53c1d599f13f 100644
--- a/sound/isa/wavefront/wavefront_midi.c
+++ b/sound/isa/wavefront/wavefront_midi.c
@@ -294,6 +294,7 @@ static int snd_wavefront_midi_input_close(struct snd_rawmidi_substream *substrea
 	        return -EIO;
 
 	spin_lock_irqsave (&midi->open, flags);
+	midi->substream_input[mpu] = NULL;
 	midi->mode[mpu] &= ~MPU401_MODE_INPUT;
 	spin_unlock_irqrestore (&midi->open, flags);
 
@@ -318,6 +319,7 @@ static int snd_wavefront_midi_output_close(struct snd_rawmidi_substream *substre
 	        return -EIO;
 
 	spin_lock_irqsave (&midi->open, flags);
+	midi->substream_output[mpu] = NULL;
 	midi->mode[mpu] &= ~MPU401_MODE_OUTPUT;
 	spin_unlock_irqrestore (&midi->open, flags);
 	return 0;
-- 
2.51.0