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=-9.8 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 329B3C433E1 for ; Thu, 20 Aug 2020 09:58:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0154C2173E for ; Thu, 20 Aug 2020 09:58:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597917515; bh=JviOPlayrNp5TUqYGsqdv/rzayIkoShqBQoDfszUVDA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=fj8VQyBMzBPYldOBxmq+wpwaB1RVlulIXEapURPL/eULEGMW8opt6P3MiGklFxT5F HEDsw3Y1enuULSuivQReYxHku2Rqve3qREOaj5P358RDH0WTRUD4lJSWmw2GgJGcze 1fVA3F0TIQmN5dAylO11pqUDpCJ4wB+5kONKzcvc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730413AbgHTJ6d (ORCPT ); Thu, 20 Aug 2020 05:58:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:42502 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729948AbgHTJ6X (ORCPT ); Thu, 20 Aug 2020 05:58:23 -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 8B17D21775; Thu, 20 Aug 2020 09:58:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597917503; bh=JviOPlayrNp5TUqYGsqdv/rzayIkoShqBQoDfszUVDA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RN/URKmOx5Q9u30oCE+POPRwRID3UT2x4tBo2U9Xfqe7BZjvkmrW3SBgS0LfH2aPx D4HsuTnxhEmwrDWH+4qjHBply8NUBhA/+yDxLCbUCLBH5GpLxGO7RIhyrAfULl9N+c zfeg4iUEGF41ui+j3//ep7ZlQg7IxhAMZMQSujIs= 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 4.9 053/212] ALSA: seq: oss: Serialize ioctls Date: Thu, 20 Aug 2020 11:20:26 +0200 Message-Id: <20200820091605.051906512@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200820091602.251285210@linuxfoundation.org> References: <20200820091602.251285210@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 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 @@ -181,10 +181,16 @@ 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