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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 5A0B8C3F359 for ; Thu, 27 Feb 2020 13:51:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2CCCD2469F for ; Thu, 27 Feb 2020 13:51:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582811519; bh=Zqa2Lb07ENrV+14mEoLnG9RRpmguim7blZ99C4OTWqM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=HETQ/WAtl5d6kIIQHN3iTJkgfu3rhtquj6Eylny4Yke+/vbBuih+FEClE/F9hux4I Sins1FtPL56yANQ6DoXBVU/NCE3zAxv9VvfxJrlSulVUX2bmbX2Iby1eZul9Gtb7j4 whOfY22mWDbGfaMhYS0khYmzi3EeTScDNT8vVPo0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731470AbgB0Nv5 (ORCPT ); Thu, 27 Feb 2020 08:51:57 -0500 Received: from mail.kernel.org ([198.145.29.99]:51226 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731463AbgB0Nvy (ORCPT ); Thu, 27 Feb 2020 08:51:54 -0500 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 834452084E; Thu, 27 Feb 2020 13:51:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582811513; bh=Zqa2Lb07ENrV+14mEoLnG9RRpmguim7blZ99C4OTWqM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JX8E1QJRxFh1aV0D+LFUNJ/myREVKmi+pojAtKGlMRpY8679w81Zq5FBtKeFHBbCw tYkWJDRCs35RkbUWA0gada1+wDDjemn5UvkU8d9omtvtsvK3683W5PnjxRalUpAGVr 35mbML/beC0hyC/5vm7ATQssBtU7j4DbLlXtVxv0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+65c6c92d04304d0a8efc@syzkaller.appspotmail.com, syzbot+e60ddfa48717579799dd@syzkaller.appspotmail.com, Takashi Iwai Subject: [PATCH 4.9 160/165] ALSA: seq: Avoid concurrent access to queue flags Date: Thu, 27 Feb 2020 14:37:14 +0100 Message-Id: <20200227132254.099080393@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200227132230.840899170@linuxfoundation.org> References: <20200227132230.840899170@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 bb51e669fa49feb5904f452b2991b240ef31bc97 upstream. The queue flags are represented in bit fields and the concurrent access may result in unexpected results. Although the current code should be mostly OK as it's only reading a field while writing other fields as KCSAN reported, it's safer to cover both with a proper spinlock protection. This patch fixes the possible concurrent read by protecting with q->owner_lock. Also the queue owner field is protected as well since it's the field to be protected by the lock itself. Reported-by: syzbot+65c6c92d04304d0a8efc@syzkaller.appspotmail.com Reported-by: syzbot+e60ddfa48717579799dd@syzkaller.appspotmail.com Link: https://lore.kernel.org/r/20200214111316.26939-2-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/seq/seq_queue.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) --- a/sound/core/seq/seq_queue.c +++ b/sound/core/seq/seq_queue.c @@ -415,6 +415,7 @@ int snd_seq_queue_check_access(int queue int snd_seq_queue_set_owner(int queueid, int client, int locked) { struct snd_seq_queue *q = queueptr(queueid); + unsigned long flags; if (q == NULL) return -EINVAL; @@ -424,8 +425,10 @@ int snd_seq_queue_set_owner(int queueid, return -EPERM; } + spin_lock_irqsave(&q->owner_lock, flags); q->locked = locked ? 1 : 0; q->owner = client; + spin_unlock_irqrestore(&q->owner_lock, flags); queue_access_unlock(q); queuefree(q); @@ -564,15 +567,17 @@ void snd_seq_queue_client_termination(in unsigned long flags; int i; struct snd_seq_queue *q; + bool matched; for (i = 0; i < SNDRV_SEQ_MAX_QUEUES; i++) { if ((q = queueptr(i)) == NULL) continue; spin_lock_irqsave(&q->owner_lock, flags); - if (q->owner == client) + matched = (q->owner == client); + if (matched) q->klocked = 1; spin_unlock_irqrestore(&q->owner_lock, flags); - if (q->owner == client) { + if (matched) { if (q->timer->running) snd_seq_timer_stop(q->timer); snd_seq_timer_reset(q->timer); @@ -764,6 +769,8 @@ void snd_seq_info_queues_read(struct snd int i, bpm; struct snd_seq_queue *q; struct snd_seq_timer *tmr; + bool locked; + int owner; for (i = 0; i < SNDRV_SEQ_MAX_QUEUES; i++) { if ((q = queueptr(i)) == NULL) @@ -775,9 +782,14 @@ void snd_seq_info_queues_read(struct snd else bpm = 0; + spin_lock_irq(&q->owner_lock); + locked = q->locked; + owner = q->owner; + spin_unlock_irq(&q->owner_lock); + snd_iprintf(buffer, "queue %d: [%s]\n", q->queue, q->name); - snd_iprintf(buffer, "owned by client : %d\n", q->owner); - snd_iprintf(buffer, "lock status : %s\n", q->locked ? "Locked" : "Free"); + snd_iprintf(buffer, "owned by client : %d\n", owner); + snd_iprintf(buffer, "lock status : %s\n", locked ? "Locked" : "Free"); snd_iprintf(buffer, "queued time events : %d\n", snd_seq_prioq_avail(q->timeq)); snd_iprintf(buffer, "queued tick events : %d\n", snd_seq_prioq_avail(q->tickq)); snd_iprintf(buffer, "timer state : %s\n", tmr->running ? "Running" : "Stopped");