From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A13DA7262E; Mon, 9 Mar 2026 10:11:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773051099; cv=none; b=h1gVtkIJziMQfQOA7m7MEFg6YoHoW6cGaZ1RCwJ3R+88/DsOLNvckHM1F/wiXHsYtVJfQXCAcfiV5tR6d3wa+MQUtoMZgO0ZuYv0VNSo+DzXPrEpoV0Ig+AdNpsgy4Ghod9Cdm92ql+52QHlIEK2tHWHgIG0pVUOjMoiJJJo6RE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773051099; c=relaxed/simple; bh=tLnmfFOZzESytsBgYKTuFVUj3SXiR9lxn7iooMlwSjM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uXNW5e2y7x5QsqmQQ6Gn1CDM3S3SgciVkCWmbZGyWAZRNK5gwy7GHUfJ6PQ+ehy6TFMLi4Js1rBzOHmbsyaOzWHybTgNAI6lgk7RZIuj5zwaNqlaWnd7cIWYQn/kkhTOkyJRgpIWaAgpY2xjfouqQSqPV92rlMLg4Gb0jRaL/Ao= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WQIgw8km; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WQIgw8km" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E85EBC4CEF7; Mon, 9 Mar 2026 10:11:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1773051099; bh=tLnmfFOZzESytsBgYKTuFVUj3SXiR9lxn7iooMlwSjM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WQIgw8kmYuDBBBt0pHS1So275S1ls7S4d26r3nG5ah6+nN8TUMclurIUX0FzJyTRy AtMFSacJXyFeaQGez/zWowB/Tk+zjwcz6Q8VlsEieKtcMgW2jjBpVhirLbLkuV0lh8 XmIr/NnSADXpG1TFFYSrWyVHYMxAdO4bfdal1NE4= Date: Mon, 9 Mar 2026 11:11:36 +0100 From: Greg KH To: Edward Adam Davis Cc: tiwai@suse.de, g@b4.vu, linux-kernel@vger.kernel.org, linux-sound@vger.kernel.org, linux-usb@vger.kernel.org, perex@perex.cz, syzbot+ae893a8901067fde2741@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com, tiwai@suse.com Subject: Re: [PATCH v2] ALSA: scarlett2: Add the number of endpoints checked was 0 Message-ID: <2026030947-ladylike-deeply-402f@gregkh> References: <87y0k1toaz.wl-tiwai@suse.de> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Mon, Mar 09, 2026 at 05:57:03PM +0800, Edward Adam Davis wrote: > The user constructed a corrupted USB device, causing the USB device > enumeration phase to fail to resolve any endpoints. This resulted in > a null pointer dereference reported in [1] when the USB sound card > driver executed probe to initialize the mixer. > > To avoid the problem reported in [1], a check was added to ensure that > the number of endpoints contained in the interface was 0 when creating > mixer controls for the Focusrite Scarlett 2nd/3rd Gen USB sound card. > > [1] > KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] > RIP: 0010:usb_endpoint_num include/uapi/linux/usb/ch9.h:479 [inline] > RIP: 0010:scarlett2_find_fc_interface sound/usb/mixer_scarlett2.c:8261 [inline] > RIP: 0010:scarlett2_init_private sound/usb/mixer_scarlett2.c:8295 [inline] > RIP: 0010:snd_scarlett2_controls_create sound/usb/mixer_scarlett2.c:8684 [inline] > RIP: 0010:snd_scarlett2_init.cold+0xbad/0x6c79 sound/usb/mixer_scarlett2.c:9407 > Call Trace: > snd_usb_mixer_apply_create_quirk+0x1c21/0x2b80 sound/usb/mixer_quirks.c:4446 > snd_usb_create_mixer+0x7a2/0x1910 sound/usb/mixer.c:3641 > usb_audio_probe+0xf6d/0x3a90 sound/usb/card.c:1033 > > Reported-by: syzbot+ae893a8901067fde2741@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=ae893a8901067fde2741 > Signed-off-by: Edward Adam Davis > --- > v1 -> v2: move the check to scarlett2 > > sound/usb/mixer_scarlett2.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/sound/usb/mixer_scarlett2.c b/sound/usb/mixer_scarlett2.c > index ef3150581eab..4b300226f16c 100644 > --- a/sound/usb/mixer_scarlett2.c > +++ b/sound/usb/mixer_scarlett2.c > @@ -9393,6 +9393,15 @@ int snd_scarlett2_init(struct usb_mixer_interface *mixer) > return 0; > } > > + if (get_iface_desc(mixer->hostif)->bNumEndpoints == 0) { > + usb_audio_err(chip, > + "%s: There are no endpoints for %04x:%04x\n", > + __func__, > + USB_ID_VENDOR(chip->usb_id), > + USB_ID_PRODUCT(chip->usb_id)); > + return 0; > + } Why not use the "normal" functions to check a USB device for the exact specific types and numbers of endpoints instead of hand-coding it all? thanks, greg k-h