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=-8.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 B34D2C31E45 for ; Thu, 13 Jun 2019 16:14:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 850A820665 for ; Thu, 13 Jun 2019 16:14:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560442470; bh=gwdxi5AAuoYgp387IoGFEKVh/fyMbDmAvT1oM3iYpVg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=1Hw0/ngwNIPO8Fq3hFShKhj9OJqzsJC5eBTUgaX7gGd45J6mltPl4nQ3BbbpYgzVH L/0gwEM/ZB3jft/fKHRAhm0paQ4NFrdYTS4T3KW5N6iWhg6pzgWsEJI0SbE/+tYFv7 C2otaDlAvIl3smGGMWSXABYW3JOW0bMZcSv6aemY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391675AbfFMQO2 (ORCPT ); Thu, 13 Jun 2019 12:14:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:59600 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731191AbfFMImZ (ORCPT ); Thu, 13 Jun 2019 04:42:25 -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 4A9E32063F; Thu, 13 Jun 2019 08:42:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560415344; bh=gwdxi5AAuoYgp387IoGFEKVh/fyMbDmAvT1oM3iYpVg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xuCYaYRIFn5Ls3DKSSdtVPltYNnS3UDuk9dgzzCkuTwzwXN0/0msSYL3DzRTjXnN+ CU/6rrqJmpA3v5JFPYYXEsknsJnIcEruxCB/yMGiXlSRVRl46S6aBDZrrFCw8UBaHM seWpWnJnbUGVM6Q1Ps+SSffaMfZzwqA8cogNG+Bs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+e4c8abb920efa77bace9@syzkaller.appspotmail.com, Takashi Iwai , Sasha Levin Subject: [PATCH 4.19 091/118] ALSA: seq: Protect in-kernel ioctl calls with mutex Date: Thu, 13 Jun 2019 10:33:49 +0200 Message-Id: <20190613075649.164602254@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190613075643.642092651@linuxfoundation.org> References: <20190613075643.642092651@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 [ Upstream commit feb689025fbb6f0aa6297d3ddf97de945ea4ad32 ] ALSA OSS sequencer calls the ioctl function indirectly via snd_seq_kernel_client_ctl(). While we already applied the protection against races between the normal ioctls and writes via the client's ioctl_mutex, this code path was left untouched. And this seems to be the cause of still remaining some rare UAF as spontaneously triggered by syzkaller. For the sake of robustness, wrap the ioctl_mutex also for the call via snd_seq_kernel_client_ctl(), too. Reported-by: syzbot+e4c8abb920efa77bace9@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin --- sound/core/seq/seq_clientmgr.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c index b55cb96d1fed..40ae8f67efde 100644 --- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -2343,14 +2343,19 @@ int snd_seq_kernel_client_ctl(int clientid, unsigned int cmd, void *arg) { const struct ioctl_handler *handler; struct snd_seq_client *client; + int err; client = clientptr(clientid); if (client == NULL) return -ENXIO; for (handler = ioctl_handlers; handler->cmd > 0; ++handler) { - if (handler->cmd == cmd) - return handler->func(client, arg); + if (handler->cmd == cmd) { + mutex_lock(&client->ioctl_mutex); + err = handler->func(client, arg); + mutex_unlock(&client->ioctl_mutex); + return err; + } } pr_debug("ALSA: seq unknown ioctl() 0x%x (type='%c', number=0x%02x)\n", -- 2.20.1