ALSA: ymfpci: check snd_ctl_new1() return value

commit e64d170 upstream.

snd_ctl_new1() can return NULL when memory allocation fails.
snd_ymfpci_create_spdif_controls() does not check the return value
before dereferencing kctl->id.device, which can lead to a NULL pointer
dereference.

Add NULL checks after snd_ctl_new1() calls and return -ENOMEM if any
fails.

Assisted-by: Opencode:DeepSeek-V4-Flash
Cc: stable@vger.kernel.org
Fixes: c9b83ae ("ALSA: ymfpci: Fix kctl->id initialization")
Signed-off-by: Zhao Dongdong <zhaodongdong@kylinos.cn>
Link: https://patch.msgid.link/tencent_4745C5DC2333325C0EDAB1EFC88A136E6809@qq.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Zhao Dongdong

sound/pci/ymfpci/ymfpci_main.c

@@ -1827,16 +1827,22 @@ int snd_ymfpci_mixer(struct snd_ymfpci *chip, int rear_switch)
 	if (snd_BUG_ON(!chip->pcm_spdif))
 		return -ENXIO;
 	kctl = snd_ctl_new1(&snd_ymfpci_spdif_default, chip);
+	if (!kctl)
+		return -ENOMEM;
 	kctl->id.device = chip->pcm_spdif->device;
 	err = snd_ctl_add(chip->card, kctl);
 	if (err < 0)
 		return err;
 	kctl = snd_ctl_new1(&snd_ymfpci_spdif_mask, chip);
+	if (!kctl)
+		return -ENOMEM;
 	kctl->id.device = chip->pcm_spdif->device;
 	err = snd_ctl_add(chip->card, kctl);
 	if (err < 0)
 		return err;
 	kctl = snd_ctl_new1(&snd_ymfpci_spdif_stream, chip);
+	if (!kctl)
+		return -ENOMEM;
 	kctl->id.device = chip->pcm_spdif->device;
 	err = snd_ctl_add(chip->card, kctl);
 	if (err < 0)