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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,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 2F789C282CE for ; Tue, 4 Jun 2019 23:23:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 006F3208C3 for ; Tue, 4 Jun 2019 23:23:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559690629; bh=MppWLxJZp3JRP/FR5+sugn5gzovZy4U+haeoJpcmMxo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=qnKb1NomtuzGGYPPp+7ipesB3AgXYGRCFa8JQaF/KzYAIhQWFMQghBiHhMXCwLUM+ 8Ew7rIjOlzM2Xi78P2+CaPO9DqXHXe+Sjci2k0cGGZCiY1t3WobgbilpB4EiLo7pO/ zokfcKyR+KLHZ9SMQuBqbxduvJ4ZVmb510rVX2Hw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727352AbfFDXXs (ORCPT ); Tue, 4 Jun 2019 19:23:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:34194 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727324AbfFDXXh (ORCPT ); Tue, 4 Jun 2019 19:23:37 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 75E1620862; Tue, 4 Jun 2019 23:23:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559690617; bh=MppWLxJZp3JRP/FR5+sugn5gzovZy4U+haeoJpcmMxo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sAOrwSuKiyZp55M1MpIkBcE6cshfu2IgQJ5vqCfdjuuhlV/MNX9WRdr25dKXudPOR MDqC/PrC/uTNLYkcVb/x8FetVgOcBZK5EBt4EIW7GH1CP5ovfr/nLApOD3RzPcBMka D2fuCCZ9hUbQdK1XpJGLDp9+ffnzB6+yvHF2E0lQ= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Takashi Iwai , syzbot+e4c8abb920efa77bace9@syzkaller.appspotmail.com, Sasha Levin Subject: [PATCH AUTOSEL 4.19 02/36] ALSA: seq: Protect in-kernel ioctl calls with mutex Date: Tue, 4 Jun 2019 19:22:57 -0400 Message-Id: <20190604232333.7185-2-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190604232333.7185-1-sashal@kernel.org> References: <20190604232333.7185-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore 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 [ 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