[alsa-devel] [patch v3] ALSA: rawmidi: fix the get next midi device ioctl

[Dan Carpenter]

If we pass in a device which is higher than SNDRV_RAWMIDI_DEVICES then
the "next device" should be -1.  This function just returns device + 1.

But the main thing is that "device + 1" can lead to a (harmless) integer
overflow and that annoys static analysis tools.

Signed-off-by: Dan Carpenter <error27 at gmail.com>
---
V2:  In the first version I made negative values return -EINVAL
V3:  We shouldn't return -EINVAL for numbers which are too large but
     just set the next device to -1.

diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index eb68326..df67605 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -829,6 +829,8 @@ static int snd_rawmidi_control_ioctl(struct snd_card *card,
 		
 		if (get_user(device, (int __user *)argp))
 			return -EFAULT;
+		if (device > SNDRV_RAWMIDI_DEVICES) /* next device is -1 */
+			device = SNDRV_RAWMIDI_DEVICES;
 		mutex_lock(&register_mutex);
 		device = device < 0 ? 0 : device + 1;
 		while (device < SNDRV_RAWMIDI_DEVICES) {