ALSA: control: Make sure that id->index does not overflow

The ALSA control code expects that the range of assigned indices to a control is
continuous and does not overflow. Currently there are no checks to enforce this.
If a control with a overflowing index range is created that control becomes
effectively inaccessible and unremovable since snd_ctl_find_id() will not be
able to find it. This patch adds a check that makes sure that controls with a
overflowing index range can not be created.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jaroslav Kysela <perex@perex.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/sound/core/control.c b/sound/core/control.c
index 8d6e4bae7407..f0b0e14497a5 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -342,6 +342,9 @@ int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
         if (snd_BUG_ON(!card || !kcontrol->info))
                 goto error;
         id = kcontrol->id;
+        if (id.index > UINT_MAX - kcontrol->count)
+                goto error;
+
         down_write(&card->controls_rwsem);
         if (snd_ctl_find_id(card, &id)) {
                 up_write(&card->controls_rwsem);