From patchwork Mon Aug 10 15:21:00 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 266630 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 342E2C433DF for ; Mon, 10 Aug 2020 15:38:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0FF3623117 for ; Mon, 10 Aug 2020 15:38:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597073891; bh=zn1+86pPO0MeKxVnkura4kzFBwLZ2uBgm92quMahL+U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kiUSmla3yOOMgrADMATXwIpvTAkqDg7wn4s8Nn/DcQkOObexrTONVXreZsxmSOJUz yFWju6q5s2duK6SPPRpnTyypU588NMO1a433j2J4IQHoEVl/f8ujt74sLuM0XqojnT pzOfkGsdLRmsJPLyn9m2P+cGDBdmkeHuNYhL8yHU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728865AbgHJPiG (ORCPT ); Mon, 10 Aug 2020 11:38:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:60170 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728513AbgHJP0Q (ORCPT ); Mon, 10 Aug 2020 11:26:16 -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 A633520658; Mon, 10 Aug 2020 15:26:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597073175; bh=zn1+86pPO0MeKxVnkura4kzFBwLZ2uBgm92quMahL+U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xiRcf4xYT7BiD6YplR7z6trVKxNHQjl66fz4OIFBneB0+aNwQIwCIoR6B7D6VXkwb F5yR9XVJNS8M75XdSMlWgbp8FaE/ztd/UYmZJvFjZ7HqlledP7td368kyNlyzsynE8 MFj0HDE6nVtq28fTgEjjqg7Dmy+0suXwTvU8sHHo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+1a54a94bd32716796edd@syzkaller.appspotmail.com, syzbot+9d2abfef257f3e2d4713@syzkaller.appspotmail.com, Hillf Danton , Takashi Iwai Subject: [PATCH 5.4 13/67] ALSA: seq: oss: Serialize ioctls Date: Mon, 10 Aug 2020 17:21:00 +0200 Message-Id: <20200810151810.080801939@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200810151809.438685785@linuxfoundation.org> References: <20200810151809.438685785@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Takashi Iwai commit 80982c7e834e5d4e325b6ce33757012ecafdf0bb upstream. Some ioctls via OSS sequencer API may race and lead to UAF when the port create and delete are performed concurrently, as spotted by a couple of syzkaller cases. This patch is an attempt to address it by serializing the ioctls with the existing register_mutex. Basically OSS sequencer API is an obsoleted interface and was designed without much consideration of the concurrency. There are very few applications with it, and the concurrent performance isn't asked, hence this "big hammer" approach should be good enough. Reported-by: syzbot+1a54a94bd32716796edd@syzkaller.appspotmail.com Reported-by: syzbot+9d2abfef257f3e2d4713@syzkaller.appspotmail.com Suggested-by: Hillf Danton Cc: Link: https://lore.kernel.org/r/20200804185815.2453-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/seq/oss/seq_oss.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) --- a/sound/core/seq/oss/seq_oss.c +++ b/sound/core/seq/oss/seq_oss.c @@ -168,10 +168,16 @@ static long odev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct seq_oss_devinfo *dp; + long rc; + dp = file->private_data; if (snd_BUG_ON(!dp)) return -ENXIO; - return snd_seq_oss_ioctl(dp, cmd, arg); + + mutex_lock(®ister_mutex); + rc = snd_seq_oss_ioctl(dp, cmd, arg); + mutex_unlock(®ister_mutex); + return rc; } #ifdef CONFIG_COMPAT