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=-8.8 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,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 CC77CC48BE3 for ; Thu, 20 Jun 2019 18:05:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2DF821479 for ; Thu, 20 Jun 2019 18:05:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561053917; bh=whJeBfMiylm/R46bOyt8WzjPdV07Kok0cuXnykji+30=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=tE8vn/Ogj1weXCZeKCdWee8z+55asgT/7W76PvZpsA2O1DlffRXoHjXcEIObyD4Bz Sq3tkg5KsRDMjO0ke3XKN4eHOEPDAIq4DLU0hhIAG05CWdWh1dwdOWBHLPniIbqDxh 54L814O7lV5zwqk2sxy7iLDq9e0ksovD8pWPo1aY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728008AbfFTSFQ (ORCPT ); Thu, 20 Jun 2019 14:05:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:58362 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727643AbfFTSFN (ORCPT ); Thu, 20 Jun 2019 14:05:13 -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 B8E4C2089C; Thu, 20 Jun 2019 18:05:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1561053912; bh=whJeBfMiylm/R46bOyt8WzjPdV07Kok0cuXnykji+30=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WkHjzBJ9h0Jobit26Ra//EqaovQMqr3FqWMnYRoLA6y5kn8ecjnFe2+SiKydZtzVX T7swg0CojnocaRXrTFsajBxSQ+kO6NvS6vxysZo8F89/Wbz/sYMKNekeiknHD1I3xB bSLaX7x7B0octsjdkmGERpgtT5KUdWyzMdL3r8rM= 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 4.9 070/117] ALSA: seq: Protect in-kernel ioctl calls with mutex Date: Thu, 20 Jun 2019 19:56:44 +0200 Message-Id: <20190620174356.877190673@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190620174351.964339809@linuxfoundation.org> References: <20190620174351.964339809@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 09491b27092e..3b1b2e9fb33e 100644 --- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -2354,14 +2354,19 @@ 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