ALSA: control: Add sanity checks for user ctl id name string

There was no check about the id string of user control elements, so we
accepted even a control element with an empty string, which is
obviously bogus.  This patch adds more sanity checks of id strings.

Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/control.c b/sound/core/control.c
index 35324a8e83c867f126256f67b493b5320b9652c7..eeb691d1911f5716bb09b8eecacd24215a31564f 100644 (file)
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -1170,6 +1170,10 @@ static int snd_ctl_elem_add(struct snd_ctl_file *file,
 
        if (info->count < 1)
                return -EINVAL;
+       if (!*info->id.name)
+               return -EINVAL;
+       if (strnlen(info->id.name, sizeof(info->id.name)) >= sizeof(info->id.name))
+               return -EINVAL;
        access = info->access == 0 ? SNDRV_CTL_ELEM_ACCESS_READWRITE :
                (info->access & (SNDRV_CTL_ELEM_ACCESS_READWRITE|
                                 SNDRV_CTL_ELEM_ACCESS_INACTIVE|