ALSA: usb: qcom: fix NULL pointer dereference in qmi_stop_session

The find_substream() call may return NULL, but the error path
dereferenced 'subs' unconditionally via dev_err(&subs->dev->dev, ...),
causing a NULL pointer dereference when subs is NULL.

Fix by switching to &uadev[idx].udev->dev which is always valid
in this context.

Signed-off-by: Pei Xiao <[email protected]>
Link: https://patch.msgid.link/86ac2939273ac853535049e60391c09d7688714e.1750755508.git.xiaopei01@kylinos.cn
Signed-off-by: Takashi Iwai <[email protected]>

Author: Pei Xiao

sound/usb/qcom/qc_audio_offload.c

@@ -759,7 +759,7 @@ static void qmi_stop_session(void)
 			subs = find_substream(pcm_card_num, info->pcm_dev_num,
 					      info->direction);
 			if (!subs || !chip || atomic_read(&chip->shutdown)) {
-				dev_err(&subs->dev->dev,
+				dev_err(&uadev[idx].udev->dev,
 					"no sub for c#%u dev#%u dir%u\n",
 					info->pcm_card_num,
 					info->pcm_dev_num,