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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C141FC32771 for ; Mon, 26 Sep 2022 10:39:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235951AbiIZKjz (ORCPT ); Mon, 26 Sep 2022 06:39:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48698 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236132AbiIZKhg (ORCPT ); Mon, 26 Sep 2022 06:37:36 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E33DB52E4E; Mon, 26 Sep 2022 03:22:08 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 17669609D1; Mon, 26 Sep 2022 10:22:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0C047C433C1; Mon, 26 Sep 2022 10:22:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1664187727; bh=2XsVl3heTzmq9Lyxn4mWy5hOBLXz/+TyJe/RKiBG/m8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wOPlNl4+H2sE7LhGymxlyCvCQKiwKOOZ/hbrFkFRnOwkdaU5Jz8mjOINMMnQyO+ff mhTiZ5BBLX7PQFAFZiHK1HDF/ABPN/ZxepV8I+ZKGyVZqMLllL/MJ4tC0nDmSQWyo/ ee8lZpTeHH4rImb6+i9VSADrs8acBhTB5xiWbDrE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jaroslav Kysela , Takashi Iwai , Sasha Levin , butt3rflyh4ck Subject: [PATCH 5.4 009/120] ALSA: pcm: oss: Fix race at SNDCTL_DSP_SYNC Date: Mon, 26 Sep 2022 12:10:42 +0200 Message-Id: <20220926100750.908254133@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220926100750.519221159@linuxfoundation.org> References: <20220926100750.519221159@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit 8423f0b6d513b259fdab9c9bf4aaa6188d054c2d ] There is a small race window at snd_pcm_oss_sync() that is called from OSS PCM SNDCTL_DSP_SYNC ioctl; namely the function calls snd_pcm_oss_make_ready() at first, then takes the params_lock mutex for the rest. When the stream is set up again by another thread between them, it leads to inconsistency, and may result in unexpected results such as NULL dereference of OSS buffer as a fuzzer spotted recently. The fix is simply to cover snd_pcm_oss_make_ready() call into the same params_lock mutex with snd_pcm_oss_make_ready_locked() variant. Reported-and-tested-by: butt3rflyh4ck Reviewed-by: Jaroslav Kysela Cc: Link: https://lore.kernel.org/r/CAFcO6XN7JDM4xSXGhtusQfS2mSBcx50VJKwQpCq=WeLt57aaZA@mail.gmail.com Link: https://lore.kernel.org/r/20220905060714.22549-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin --- sound/core/oss/pcm_oss.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c index ad4e0af2d0d0..51d2911366e9 100644 --- a/sound/core/oss/pcm_oss.c +++ b/sound/core/oss/pcm_oss.c @@ -1661,13 +1661,14 @@ static int snd_pcm_oss_sync(struct snd_pcm_oss_file *pcm_oss_file) runtime = substream->runtime; if (atomic_read(&substream->mmap_count)) goto __direct; - if ((err = snd_pcm_oss_make_ready(substream)) < 0) - return err; atomic_inc(&runtime->oss.rw_ref); if (mutex_lock_interruptible(&runtime->oss.params_lock)) { atomic_dec(&runtime->oss.rw_ref); return -ERESTARTSYS; } + err = snd_pcm_oss_make_ready_locked(substream); + if (err < 0) + goto unlock; format = snd_pcm_oss_format_from(runtime->oss.format); width = snd_pcm_format_physical_width(format); if (runtime->oss.buffer_used > 0) { -- 2.35.1