ALSA: control: Avoid kernel warnings from tlv ioctl with numid 0

commit c0bcdbdff3ff73a54161fca3cb8b6cdbd0bb8762 upstream.

When a TLV ioctl with numid zero is handled, the driver may spew a
kernel warning with a stack trace at each call.  The check was
intended obviously only for a kernel driver, but not for a user
interaction.  Let's fix it.

This was spotted by syzkaller fuzzer.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/sound/core/control.c b/sound/core/control.c
index 1ba5d33..96c62e5 100644 (file)
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -1321,6 +1321,8 @@ static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
                return -EFAULT;
        if (tlv.length < sizeof(unsigned int) * 2)
                return -EINVAL;
+       if (!tlv.numid)
+               return -EINVAL;
        down_read(&card->controls_rwsem);
        kctl = snd_ctl_find_numid(card, tlv.numid);
        if (kctl == NULL) {