[patch] ALSA: rawmidi: cleanup the get next midi device ioctl

[Dan Carpenter <error27@xxxxxxxxx>]

I'm doing an audit to find integer overflows and my static checker
complained that in the original code "device + 1" could overflow.  The
overflow is harmless, but it's still worth cleaning up.  The other thing
that I noticed is that if you pass in a device which is higher than
SNDRV_RAWMIDI_DEVICES then it doesn't return an error code but just
tells you that the next device is "device + 1".

I have rewritten it to just return -EINVAL if you pass in a bogus value
that's either too high or too low.  

Signed-off-by: Dan Carpenter <error27@xxxxxxxxx>

diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index eb68326..f944180 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -829,8 +829,12 @@ static int snd_rawmidi_control_ioctl(struct snd_card *card,
 		
 		if (get_user(device, (int __user *)argp))
 			return -EFAULT;
+		if (device < 0)
+			return -EINVAL;
+		if (device > SNDRV_RAWMIDI_DEVICES)
+			return -EINVAL;
 		mutex_lock(&register_mutex);
-		device = device < 0 ? 0 : device + 1;
+		device++;
 		while (device < SNDRV_RAWMIDI_DEVICES) {
 			if (snd_rawmidi_search(card, device))
 				break;
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