From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29736C2D0D2 for ; Fri, 20 Dec 2019 09:46:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 05FF8227BF for ; Fri, 20 Dec 2019 09:46:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727192AbfLTJqw (ORCPT ); Fri, 20 Dec 2019 04:46:52 -0500 Received: from mx2.suse.de ([195.135.220.15]:58020 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726210AbfLTJqw (ORCPT ); Fri, 20 Dec 2019 04:46:52 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 67ACFACF6; Fri, 20 Dec 2019 09:46:50 +0000 (UTC) Date: Fri, 20 Dec 2019 10:46:50 +0100 Message-ID: From: Takashi Iwai To: Johan Hovold Cc: Jaroslav Kysela , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, stable Subject: Re: [PATCH] ALSA: usb-audio: fix set_format altsetting sanity check In-Reply-To: <20191220093134.1248-1-johan@kernel.org> References: <20191220093134.1248-1-johan@kernel.org> 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/25.3 (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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 20 Dec 2019 10:31:34 +0100, Johan Hovold wrote: > > Make sure to check the return value of usb_altnum_to_altsetting() to > avoid dereferencing a NULL pointer when the requested alternate settings > is missing. > > The format altsetting number may come from a quirk table and there does > not seem to be any other validation of it (the corresponding index is > checked however). > > Fixes: b099b9693d23 ("ALSA: usb-audio: Avoid superfluous usb_set_interface() calls") > Cc: stable # 4.18 > Signed-off-by: Johan Hovold > --- > sound/usb/pcm.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c > index 9c8930bb00c8..73dd9d21bb42 100644 > --- a/sound/usb/pcm.c > +++ b/sound/usb/pcm.c > @@ -506,9 +506,9 @@ static int set_format(struct snd_usb_substream *subs, struct audioformat *fmt) > if (WARN_ON(!iface)) > return -EINVAL; > alts = usb_altnum_to_altsetting(iface, fmt->altsetting); > - altsd = get_iface_desc(alts); > - if (WARN_ON(altsd->bAlternateSetting != fmt->altsetting)) > + if (WARN_ON(!alts)) > return -EINVAL; Do we need WARN_ON() here? If this may hit on syzbot, it'll stop at this point because of panic_on_warn. thanks, Takashi > + altsd = get_iface_desc(alts); > > if (fmt == subs->cur_audiofmt) > return 0; > -- > 2.24.1 >