From: Takashi Iwai <tiwai@suse.de>
Date: Mon, 18 Jan 2016 13:12:40 +0000 (+0100)
Subject: ALSA: control: Avoid kernel warnings from tlv ioctl with numid 0
X-Git-Tag: firefly_0821_release~3391^2~164
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=66bd949b3a3680400ff53f4f847e16ad40a9edbd;p=firefly-linux-kernel-4.4.55.git

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/sound/core/control.c b/sound/core/control.c
index 196a6fe100ca..a85d45595d02 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -1405,6 +1405,8 @@ 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) {