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 D1557C46470 for ; Tue, 4 Jun 2019 23:27:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA731206B8 for ; Tue, 4 Jun 2019 23:27:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559690868; bh=8qDN8Z84RH30uv7GTcEPp/6Cbc43X8MMg4KvN0LFjN8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=CHV3d9LWlaYSMsLp6v8QvWChkEc09QH/VbrIcQYBoJCqUuLL0Y1Xe1YrjcxOGbR1w /RLAfkqNgeg8UxNVp+MYFoXO+CstWXs9nu/vWZepy6nlnr2OaOxdBZWQ0Z+0K64zdA LArKXIUVMQIKjiBdOGzi7bgl/Buakj1pTzjyEaxU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727864AbfFDXZJ (ORCPT ); Tue, 4 Jun 2019 19:25:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:36626 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727820AbfFDXZI (ORCPT ); Tue, 4 Jun 2019 19:25:08 -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 5FBFE206C1; Tue, 4 Jun 2019 23:25:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559690708; bh=8qDN8Z84RH30uv7GTcEPp/6Cbc43X8MMg4KvN0LFjN8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pdqzPZY15i8GF+OjniAbTZjBSSJYB+u6GRX23nfNQWvkzAVctSZLdjR2pJf5WD2Tu qeMn7HQ0WWa3SM1V7TB4fJCpA3E9Uw0Hh143p5nuLMwO5GTXSvzR6w4+GTb1wVsNI4 Lt+SRMoPLglSabCaGVGhiC37J0w3NOywtz1tWonw= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Takashi Iwai , syzbot+9437020c82413d00222d@syzkaller.appspotmail.com, Sasha Levin Subject: [PATCH AUTOSEL 4.9 03/17] ALSA: seq: Fix race of get-subscription call vs port-delete ioctls Date: Tue, 4 Jun 2019 19:24:44 -0400 Message-Id: <20190604232459.7745-3-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190604232459.7745-1-sashal@kernel.org> References: <20190604232459.7745-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Takashi Iwai [ Upstream commit 2eabc5ec8ab4d4748a82050dfcb994119b983750 ] The snd_seq_ioctl_get_subscription() retrieves the port subscriber information as a pointer, while the object isn't protected, hence it may be deleted before the actual reference. This race was spotted by syzkaller and may lead to a UAF. The fix is simply copying the data in the lookup function that performs in the rwsem to protect against the deletion. Reported-by: syzbot+9437020c82413d00222d@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin --- sound/core/seq/seq_clientmgr.c | 10 ++-------- sound/core/seq/seq_ports.c | 13 ++++++++----- sound/core/seq/seq_ports.h | 5 +++-- 3 files changed, 13 insertions(+), 15 deletions(-) diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c index 3b1b2e9fb33e..881c965555c5 100644 --- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -1905,20 +1905,14 @@ static int snd_seq_ioctl_get_subscription(struct snd_seq_client *client, int result; struct snd_seq_client *sender = NULL; struct snd_seq_client_port *sport = NULL; - struct snd_seq_subscribers *p; result = -EINVAL; if ((sender = snd_seq_client_use_ptr(subs->sender.client)) == NULL) goto __end; if ((sport = snd_seq_port_use_ptr(sender, subs->sender.port)) == NULL) goto __end; - p = snd_seq_port_get_subscription(&sport->c_src, &subs->dest); - if (p) { - result = 0; - *subs = p->info; - } else - result = -ENOENT; - + result = snd_seq_port_get_subscription(&sport->c_src, &subs->dest, + subs); __end: if (sport) snd_seq_port_unlock(sport); diff --git a/sound/core/seq/seq_ports.c b/sound/core/seq/seq_ports.c index f04714d70bf7..faf7ceffbeca 100644 --- a/sound/core/seq/seq_ports.c +++ b/sound/core/seq/seq_ports.c @@ -635,20 +635,23 @@ int snd_seq_port_disconnect(struct snd_seq_client *connector, /* get matched subscriber */ -struct snd_seq_subscribers *snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp, - struct snd_seq_addr *dest_addr) +int snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp, + struct snd_seq_addr *dest_addr, + struct snd_seq_port_subscribe *subs) { - struct snd_seq_subscribers *s, *found = NULL; + struct snd_seq_subscribers *s; + int err = -ENOENT; down_read(&src_grp->list_mutex); list_for_each_entry(s, &src_grp->list_head, src_list) { if (addr_match(dest_addr, &s->info.dest)) { - found = s; + *subs = s->info; + err = 0; break; } } up_read(&src_grp->list_mutex); - return found; + return err; } /* diff --git a/sound/core/seq/seq_ports.h b/sound/core/seq/seq_ports.h index 26bd71f36c41..06003b36652e 100644 --- a/sound/core/seq/seq_ports.h +++ b/sound/core/seq/seq_ports.h @@ -135,7 +135,8 @@ int snd_seq_port_subscribe(struct snd_seq_client_port *port, struct snd_seq_port_subscribe *info); /* get matched subscriber */ -struct snd_seq_subscribers *snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp, - struct snd_seq_addr *dest_addr); +int snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp, + struct snd_seq_addr *dest_addr, + struct snd_seq_port_subscribe *subs); #endif -- 2.20.1