sound: control: fix minimum TLV length

Allow TLV blocks that do not have any values; the smallest possible TLV
is an empty container or one where the information is only in the tag.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

diff --git a/sound/core/control.c b/sound/core/control.c
index 6a4764dcb18002831b0dd08536992ceea887e58c..439ce64f9d82edfcfdd867d152dc469969cc1ead 100644 (file)
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -1100,7 +1100,7 @@ static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
 
        if (copy_from_user(&tlv, _tlv, sizeof(tlv)))
                return -EFAULT;
-       if (tlv.length < sizeof(unsigned int) * 3)
+       if (tlv.length < sizeof(unsigned int) * 2)
                return -EINVAL;
        down_read(&card->controls_rwsem);
        kctl = snd_ctl_find_numid(card, tlv.numid);