ALSA: sound/isa: use memdup_user()

Remove open-coded memdup_user().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/isa/wavefront/wavefront_synth.c b/sound/isa/wavefront/wavefront_synth.c
index beb312c..5d4ff48 100644
--- a/sound/isa/wavefront/wavefront_synth.c
+++ b/sound/isa/wavefront/wavefront_synth.c
@@ -1664,12 +1664,11 @@
 		break;
 
 	case WFCTL_WFCMD:
-		wc = kmalloc(sizeof(*wc), GFP_KERNEL);
-		if (! wc)
-			return -ENOMEM;
-		if (copy_from_user (wc, argp, sizeof (*wc)))
-			err = -EFAULT;
-		else if (wavefront_synth_control (acard, wc) < 0)
+		wc = memdup_user(argp, sizeof(*wc));
+		if (IS_ERR(wc))
+			return PTR_ERR(wc);
+
+		if (wavefront_synth_control (acard, wc) < 0)
 			err = -EIO;
 		else if (copy_to_user (argp, wc, sizeof (*wc)))
 			err = -EFAULT;