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=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 22981C433E2 for ; Mon, 20 Jul 2020 15:43:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F36392064B for ; Mon, 20 Jul 2020 15:43:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595259836; bh=PKbze4aIN2Tiq+hHX/fexUrT/75/AE9fmKBYSnkr+oY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JvQCUfsX1/Sio0SzKAryFDPRqS+NnBoW5jC1yYVzLRYjlt+ktwJ90ZcwGH/dHw55U 24dnRxvwXHLS4MS5r4yB//dzp0BnmhbTpEFe3cMmEZqiG6hln1UZ+Scoj5+3HXwiuh t4txijt13SDLH5+ckpk9EXe5Bo5ffpBj4Nl3xVJI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730326AbgGTPny (ORCPT ); Mon, 20 Jul 2020 11:43:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:37298 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729571AbgGTPnt (ORCPT ); Mon, 20 Jul 2020 11:43:49 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CD1AF2064B; Mon, 20 Jul 2020 15:43:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595259828; bh=PKbze4aIN2Tiq+hHX/fexUrT/75/AE9fmKBYSnkr+oY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N+tbrBEjTzGSWFKWu8Afi3olui7rrpzeko7i4SEJAGggeuCSrMK8Hm/9pRPYcapVP F4yD51n98kA/S4hwT4tEmgY1jpvliUoajcv3VEQn8sldxuxJrbxWrD3tqS1FcmOXrY IoiFB6OYxnw3vBK9EIvhRLubG+yaSxbvYDfcXHi0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+0f4ecfe6a2c322c81728@syzkaller.appspotmail.com, syzbot+5f1d24c49c1d2c427497@syzkaller.appspotmail.com, Takashi Iwai Subject: [PATCH 4.9 63/86] ALSA: usb-audio: Fix race against the error recovery URB submission Date: Mon, 20 Jul 2020 17:36:59 +0200 Message-Id: <20200720152756.340958934@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200720152753.138974850@linuxfoundation.org> References: <20200720152753.138974850@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Takashi Iwai commit 9b7e5208a941e2e491a83eb5fa83d889e888fa2f upstream. USB MIDI driver has an error recovery mechanism to resubmit the URB in the delayed timer handler, and this may race with the standard start / stop operations. Although both start and stop operations themselves don't race with each other due to the umidi->mutex protection, but this isn't applied to the timer handler. For fixing this potential race, the following changes are applied: - Since the timer handler can't use the mutex, we apply the umidi->disc_lock protection at each input stream URB submission; this also needs to change the GFP flag to GFP_ATOMIC - Add a check of the URB refcount and skip if already submitted - Move the timer cancel call at disconnection to the beginning of the procedure; this assures the in-flight timer handler is gone properly before killing all pending URBs Reported-by: syzbot+0f4ecfe6a2c322c81728@syzkaller.appspotmail.com Reported-by: syzbot+5f1d24c49c1d2c427497@syzkaller.appspotmail.com Cc: Link: https://lore.kernel.org/r/20200710160656.16819-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/usb/midi.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) --- a/sound/usb/midi.c +++ b/sound/usb/midi.c @@ -1477,6 +1477,8 @@ void snd_usbmidi_disconnect(struct list_ spin_unlock_irq(&umidi->disc_lock); up_write(&umidi->disc_rwsem); + del_timer_sync(&umidi->error_timer); + for (i = 0; i < MIDI_MAX_ENDPOINTS; ++i) { struct snd_usb_midi_endpoint *ep = &umidi->endpoints[i]; if (ep->out) @@ -1503,7 +1505,6 @@ void snd_usbmidi_disconnect(struct list_ ep->in = NULL; } } - del_timer_sync(&umidi->error_timer); } EXPORT_SYMBOL(snd_usbmidi_disconnect); @@ -2260,16 +2261,22 @@ void snd_usbmidi_input_stop(struct list_ } EXPORT_SYMBOL(snd_usbmidi_input_stop); -static void snd_usbmidi_input_start_ep(struct snd_usb_midi_in_endpoint *ep) +static void snd_usbmidi_input_start_ep(struct snd_usb_midi *umidi, + struct snd_usb_midi_in_endpoint *ep) { unsigned int i; + unsigned long flags; if (!ep) return; for (i = 0; i < INPUT_URBS; ++i) { struct urb *urb = ep->urbs[i]; - urb->dev = ep->umidi->dev; - snd_usbmidi_submit_urb(urb, GFP_KERNEL); + spin_lock_irqsave(&umidi->disc_lock, flags); + if (!atomic_read(&urb->use_count)) { + urb->dev = ep->umidi->dev; + snd_usbmidi_submit_urb(urb, GFP_ATOMIC); + } + spin_unlock_irqrestore(&umidi->disc_lock, flags); } } @@ -2285,7 +2292,7 @@ void snd_usbmidi_input_start(struct list if (umidi->input_running || !umidi->opened[1]) return; for (i = 0; i < MIDI_MAX_ENDPOINTS; ++i) - snd_usbmidi_input_start_ep(umidi->endpoints[i].in); + snd_usbmidi_input_start_ep(umidi, umidi->endpoints[i].in); umidi->input_running = 1; } EXPORT_SYMBOL(snd_usbmidi_input_start);