releases/3.14.60/alsa-control-avoid-kernel-warnings-from-tlv-ioctl-with-numid-0.patch

   1 From c0bcdbdff3ff73a54161fca3cb8b6cdbd0bb8762 Mon Sep 17 00:00:00 2001
   2 From: Takashi Iwai <tiwai@suse.de>
   3 Date: Mon, 18 Jan 2016 14:12:40 +0100
   4 Subject: ALSA: control: Avoid kernel warnings from tlv ioctl with numid 0
   5
   6 From: Takashi Iwai <tiwai@suse.de>
   7
   8 commit c0bcdbdff3ff73a54161fca3cb8b6cdbd0bb8762 upstream.
   9
  10 When a TLV ioctl with numid zero is handled, the driver may spew a
  11 kernel warning with a stack trace at each call.  The check was
  12 intended obviously only for a kernel driver, but not for a user
  13 interaction.  Let's fix it.
  14
  15 This was spotted by syzkaller fuzzer.
  16
  17 Reported-by: Dmitry Vyukov <dvyukov@google.com>
  18 Signed-off-by: Takashi Iwai <tiwai@suse.de>
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20
  21 ---
  22  sound/core/control.c |    2 ++
  23  1 file changed, 2 insertions(+)
  24
  25 --- a/sound/core/control.c
  26 +++ b/sound/core/control.c
  27 @@ -1325,6 +1325,8 @@ static int snd_ctl_tlv_ioctl(struct snd_
  28                 return -EFAULT;
  29         if (tlv.length < sizeof(unsigned int) * 2)
  30                 return -EINVAL;
  31 +       if (!tlv.numid)
  32 +               return -EINVAL;
  33         down_read(&card->controls_rwsem);
  34         kctl = snd_ctl_find_numid(card, tlv.numid);
  35         if (kctl == NULL) {