From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755062AbcARNRg (ORCPT ); Mon, 18 Jan 2016 08:17:36 -0500 Received: from mx2.suse.de ([195.135.220.15]:53949 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754902AbcARNRd (ORCPT ); Mon, 18 Jan 2016 08:17:33 -0500 Date: Mon, 18 Jan 2016 14:17:27 +0100 Message-ID: From: Takashi Iwai To: "Dmitry Vyukov" Cc: , "Jaroslav Kysela" , "Takashi Sakamoto" , "LKML" , "Alexander Potapenko" , "Kostya Serebryany" , "syzkaller" , "Sasha Levin" Subject: Re: sound: BUG in snd_ctl_find_numid In-Reply-To: References: User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/24.5 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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 Cc: Signed-off-by: Takashi Iwai --- 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