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SubjectRe: sound: BUG in snd_ctl_find_numid
On Mon, 18 Jan 2016 13:59:49 +0100,
Dmitry Vyukov wrote:
>
> Hello,
>
> The following program triggers a BUG in snd_ctl_find_numid:

Do I understand correctly that you meant a kernel WARNING with a stack
trace as a "BUG"? If so, the patch below should cover it.


thanks,

Takashi

-- 8< --
From: Takashi Iwai <tiwai@suse.de>
Subject: [PATCH] ALSA: control: Avoid kernel warnings from tlv ioctl with
numid 0

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
sound/core/control.c | 2 ++
1 file changed, 2 insertions(+)

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) {
--
2.7.0

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