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 alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2288DC3DA40 for ; Mon, 26 Jun 2023 21:53:56 +0000 (UTC) Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id 2244585D; Mon, 26 Jun 2023 23:53:04 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz 2244585D DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1687816434; bh=yq3UlTtcjThyf//f4f6HPc3q0O4+oKR0P4XfthwA5Es=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-Id: List-Archive:List-Help:List-Owner:List-Post:List-Subscribe: List-Unsubscribe:From; b=Alg4zybj+A0GHs7HU+DnZAd1qCFh7mpMMVYVTuY64Aa1mJT+O53BxMIyxzqHiWoNW XGIiCWQVLEgjjFwKp7kGwWpkLLoywv/msXNoiURamGxzOMnUKB1CWbmJWmDDYJUd/x tY2YyFKc4hbym0Lt22BZfPNCCbRYbVAmCPBcWEwg= Received: by alsa1.perex.cz (Postfix, from userid 50401) id 46850F80588; Mon, 26 Jun 2023 23:51:57 +0200 (CEST) Received: from mailman-core.alsa-project.org (mailman-core.alsa-project.org [10.254.200.10]) by alsa1.perex.cz (Postfix) with ESMTP id ABD8BF80570; Mon, 26 Jun 2023 23:51:56 +0200 (CEST) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 59784F80534; Mon, 26 Jun 2023 23:51:28 +0200 (CEST) Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id 5A05BF80169 for ; Mon, 26 Jun 2023 23:51:26 +0200 (CEST) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz 5A05BF80169 Authentication-Results: alsa1.perex.cz; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=O/wseL+q Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D328E60FB4; Mon, 26 Jun 2023 21:51:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FF61C433C8; Mon, 26 Jun 2023 21:51:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1687816283; bh=yq3UlTtcjThyf//f4f6HPc3q0O4+oKR0P4XfthwA5Es=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O/wseL+qSl8dQoKlC7bx9bt2tWRKa2jwD3AeAb69kXoDxdg7PI3YXQYx+iqwQXLvE MGjN/x8ln+oboRAzBPHsPJFmlpX7mN3xmUQ3+nA4pk2gl2K8gqz5uaBhg5iZY1Mn2S U0lH6VqXVBPN8jFcxx95R8A5uzLk+KoywzjwdTv5b18VLAQkqmzpkEMEV7GTvxba8/ tIGyQ1MWeqokg4P7LPCP5N0SSLsYqb2uusi5IBRdyN5bJM/s7yvR09Vxs1hbY7AwFV abXyeCmu+OUjbq175kI7rAgjsgvhzDhBFuENYCCBI4T318lSCiO+iLKffJi8h3W51f s1GJws27qCXdQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Takashi Iwai , "Gong, Sishuai" , Sasha Levin , perex@perex.cz, tiwai@suse.com, alsa-devel@alsa-project.org Subject: [PATCH AUTOSEL 5.4 6/6] ALSA: seq: oss: Fix racy open/close of MIDI devices Date: Mon, 26 Jun 2023 17:51:16 -0400 Message-Id: <20230626215116.179581-6-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230626215116.179581-1-sashal@kernel.org> References: <20230626215116.179581-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.4.248 Content-Transfer-Encoding: 8bit Message-ID-Hash: OVADJLUMUXGQEG5DF2GXL3TLTWHU5SGO X-Message-ID-Hash: OVADJLUMUXGQEG5DF2GXL3TLTWHU5SGO X-MailFrom: sashal@kernel.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-alsa-devel.alsa-project.org-0; header-match-alsa-devel.alsa-project.org-1; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.8 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" Archived-At: <> List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: From: Takashi Iwai [ Upstream commit 297224fc0922e7385573a30c29ffdabb67f27b7d ] Although snd_seq_oss_midi_open() and snd_seq_oss_midi_close() can be called concurrently from different code paths, we have no proper data protection against races. Introduce open_mutex to each seq_oss_midi object for avoiding the races. Reported-by: "Gong, Sishuai" Closes: https://lore.kernel.org/r/7DC9AF71-F481-4ABA-955F-76C535661E33@purdue.edu Link: https://lore.kernel.org/r/20230612125533.27461-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin --- sound/core/seq/oss/seq_oss_midi.c | 35 +++++++++++++++++++------------ 1 file changed, 22 insertions(+), 13 deletions(-) diff --git a/sound/core/seq/oss/seq_oss_midi.c b/sound/core/seq/oss/seq_oss_midi.c index f73ee0798aeab..be80ce72e0c72 100644 --- a/sound/core/seq/oss/seq_oss_midi.c +++ b/sound/core/seq/oss/seq_oss_midi.c @@ -37,6 +37,7 @@ struct seq_oss_midi { struct snd_midi_event *coder; /* MIDI event coder */ struct seq_oss_devinfo *devinfo; /* assigned OSSseq device */ snd_use_lock_t use_lock; + struct mutex open_mutex; }; @@ -171,6 +172,7 @@ snd_seq_oss_midi_check_new_port(struct snd_seq_port_info *pinfo) mdev->flags = pinfo->capability; mdev->opened = 0; snd_use_lock_init(&mdev->use_lock); + mutex_init(&mdev->open_mutex); /* copy and truncate the name of synth device */ strlcpy(mdev->name, pinfo->name, sizeof(mdev->name)); @@ -319,14 +321,16 @@ snd_seq_oss_midi_open(struct seq_oss_devinfo *dp, int dev, int fmode) int perm; struct seq_oss_midi *mdev; struct snd_seq_port_subscribe subs; + int err; if ((mdev = get_mididev(dp, dev)) == NULL) return -ENODEV; + mutex_lock(&mdev->open_mutex); /* already used? */ if (mdev->opened && mdev->devinfo != dp) { - snd_use_lock_free(&mdev->use_lock); - return -EBUSY; + err = -EBUSY; + goto unlock; } perm = 0; @@ -336,14 +340,14 @@ snd_seq_oss_midi_open(struct seq_oss_devinfo *dp, int dev, int fmode) perm |= PERM_READ; perm &= mdev->flags; if (perm == 0) { - snd_use_lock_free(&mdev->use_lock); - return -ENXIO; + err = -ENXIO; + goto unlock; } /* already opened? */ if ((mdev->opened & perm) == perm) { - snd_use_lock_free(&mdev->use_lock); - return 0; + err = 0; + goto unlock; } perm &= ~mdev->opened; @@ -368,13 +372,17 @@ snd_seq_oss_midi_open(struct seq_oss_devinfo *dp, int dev, int fmode) } if (! mdev->opened) { - snd_use_lock_free(&mdev->use_lock); - return -ENXIO; + err = -ENXIO; + goto unlock; } mdev->devinfo = dp; + err = 0; + + unlock: + mutex_unlock(&mdev->open_mutex); snd_use_lock_free(&mdev->use_lock); - return 0; + return err; } /* @@ -388,10 +396,9 @@ snd_seq_oss_midi_close(struct seq_oss_devinfo *dp, int dev) if ((mdev = get_mididev(dp, dev)) == NULL) return -ENODEV; - if (! mdev->opened || mdev->devinfo != dp) { - snd_use_lock_free(&mdev->use_lock); - return 0; - } + mutex_lock(&mdev->open_mutex); + if (!mdev->opened || mdev->devinfo != dp) + goto unlock; memset(&subs, 0, sizeof(subs)); if (mdev->opened & PERM_WRITE) { @@ -410,6 +417,8 @@ snd_seq_oss_midi_close(struct seq_oss_devinfo *dp, int dev) mdev->opened = 0; mdev->devinfo = NULL; + unlock: + mutex_unlock(&mdev->open_mutex); snd_use_lock_free(&mdev->use_lock); return 0; } -- 2.39.2