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=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, UNWANTED_LANGUAGE_BODY,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 769BFC43216 for ; Mon, 26 Jul 2021 16:20:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 647CC60FEB for ; Mon, 26 Jul 2021 16:20:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238124AbhGZPjU (ORCPT ); Mon, 26 Jul 2021 11:39:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:37026 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237316AbhGZPWX (ORCPT ); Mon, 26 Jul 2021 11:22:23 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C16E360FC0; Mon, 26 Jul 2021 15:53:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1627314791; bh=Pz5znl3oCRXX/Ot8HGsKGVlif7ze/TLXcSlFz9LJoDk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=k3qSTK2sVECCexjtW+K4F3Wsee1+44O/ea5F2jtbx/xkXIPCu/07w4MrVxsG+nWql KzoNEW1nmosrEiM9ncewD8uRNzOkRm3o6vNB5/hjdKvAqUHv3+FgVlbBdkHPCb+XJ7 PD1Ad2FZkF2VTm3OqIP2LvaiaZRV34C7tv3vD1Hk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jia-Ju Bai , Takashi Iwai Subject: [PATCH 4.19 093/120] ALSA: sb: Fix potential ABBA deadlock in CSP driver Date: Mon, 26 Jul 2021 17:39:05 +0200 Message-Id: <20210726153835.380618346@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210726153832.339431936@linuxfoundation.org> References: <20210726153832.339431936@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Takashi Iwai commit 1c2b9519159b470ef24b2638f4794e86e2952ab7 upstream. SB16 CSP driver may hit potentially a typical ABBA deadlock in two code paths: In snd_sb_csp_stop(): spin_lock_irqsave(&p->chip->mixer_lock, flags); spin_lock(&p->chip->reg_lock); In snd_sb_csp_load(): spin_lock_irqsave(&p->chip->reg_lock, flags); spin_lock(&p->chip->mixer_lock); Also the similar pattern is seen in snd_sb_csp_start(). Although the practical impact is very small (those states aren't triggered in the same running state and this happens only on a real hardware, decades old ISA sound boards -- which must be very difficult to find nowadays), it's a real scenario and has to be fixed. This patch addresses those deadlocks by splitting the locks in snd_sb_csp_start() and snd_sb_csp_stop() for avoiding the nested locks. Reported-by: Jia-Ju Bai Cc: Link: https://lore.kernel.org/r/7b0fcdaf-cd4f-4728-2eae-48c151a92e10@gmail.com Link: https://lore.kernel.org/r/20210716132723.13216-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/isa/sb/sb16_csp.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/sound/isa/sb/sb16_csp.c +++ b/sound/isa/sb/sb16_csp.c @@ -828,6 +828,7 @@ static int snd_sb_csp_start(struct snd_s mixR = snd_sbmixer_read(p->chip, SB_DSP4_PCM_DEV + 1); snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL & 0x7); snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR & 0x7); + spin_unlock_irqrestore(&p->chip->mixer_lock, flags); spin_lock(&p->chip->reg_lock); set_mode_register(p->chip, 0xc0); /* c0 = STOP */ @@ -867,6 +868,7 @@ static int snd_sb_csp_start(struct snd_s spin_unlock(&p->chip->reg_lock); /* restore PCM volume */ + spin_lock_irqsave(&p->chip->mixer_lock, flags); snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL); snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR); spin_unlock_irqrestore(&p->chip->mixer_lock, flags); @@ -892,6 +894,7 @@ static int snd_sb_csp_stop(struct snd_sb mixR = snd_sbmixer_read(p->chip, SB_DSP4_PCM_DEV + 1); snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL & 0x7); snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR & 0x7); + spin_unlock_irqrestore(&p->chip->mixer_lock, flags); spin_lock(&p->chip->reg_lock); if (p->running & SNDRV_SB_CSP_ST_QSOUND) { @@ -906,6 +909,7 @@ static int snd_sb_csp_stop(struct snd_sb spin_unlock(&p->chip->reg_lock); /* restore PCM volume */ + spin_lock_irqsave(&p->chip->mixer_lock, flags); snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV, mixL); snd_sbmixer_write(p->chip, SB_DSP4_PCM_DEV + 1, mixR); spin_unlock_irqrestore(&p->chip->mixer_lock, flags);