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=-10.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 BEB3DC43387 for ; Mon, 7 Jan 2019 12:45:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8DD792183E for ; Mon, 7 Jan 2019 12:45:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546865124; bh=uZdrzunQhlW0MKQTLJomRgH7vmquQpJYwidV9aggTxA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=EjGHnqNwxgtHkpChwA2lmzjXk/k2Vq4X7be8CsbPPI8AXEVQW1QI1947QLBsWeyEx 0OTmKpbGu5jT95nO4mJM8+IcLlwbR5zLOcLX0lhKrrofONv8HPmyxoq51y2g7A6bS6 FLpaAm79U3wddBJAVe0qtX/U9734alNixNU6sSl8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728858AbfAGMpX (ORCPT ); Mon, 7 Jan 2019 07:45:23 -0500 Received: from mail.kernel.org ([198.145.29.99]:34482 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728844AbfAGMpT (ORCPT ); Mon, 7 Jan 2019 07:45:19 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.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 C03D521873; Mon, 7 Jan 2019 12:45:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546865119; bh=uZdrzunQhlW0MKQTLJomRgH7vmquQpJYwidV9aggTxA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Cat1rLs6Xzxw/797KNukk/mL3zyYc19tLt0wR8oWxAzMHa2hph6hW4yC8mabEvztr AwaLFNfJ8UKDXnbD3k7WnoY2DSalULFE+FQxNamfJuikIxL93lNUX1OQqstNw3u/c2 nSn3uC/XJJuKdi6mZoOXSWzxGRtz17aNXQNmZCh8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Cong Wang , "David S. Miller" , syzbot+ae6bb869cbed29b29040@syzkaller.appspotmail.com Subject: [PATCH 4.19 001/170] ax25: fix a use-after-free in ax25_fillin_cb() Date: Mon, 7 Jan 2019 13:30:28 +0100 Message-Id: <20190107104453.089925136@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190107104452.953560660@linuxfoundation.org> References: <20190107104452.953560660@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore 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 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cong Wang [ Upstream commit c433570458e49bccea5c551df628d058b3526289 ] There are multiple issues here: 1. After freeing dev->ax25_ptr, we need to set it to NULL otherwise we may use a dangling pointer. 2. There is a race between ax25_setsockopt() and device notifier as reported by syzbot. Close it by holding RTNL lock. 3. We need to test if dev->ax25_ptr is NULL before using it. Reported-and-tested-by: syzbot+ae6bb869cbed29b29040@syzkaller.appspotmail.com Signed-off-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ax25/af_ax25.c | 11 +++++++++-- net/ax25/ax25_dev.c | 2 ++ 2 files changed, 11 insertions(+), 2 deletions(-) --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -653,15 +653,22 @@ static int ax25_setsockopt(struct socket break; } - dev = dev_get_by_name(&init_net, devname); + rtnl_lock(); + dev = __dev_get_by_name(&init_net, devname); if (!dev) { + rtnl_unlock(); res = -ENODEV; break; } ax25->ax25_dev = ax25_dev_ax25dev(dev); + if (!ax25->ax25_dev) { + rtnl_unlock(); + res = -ENODEV; + break; + } ax25_fillin_cb(ax25, ax25->ax25_dev); - dev_put(dev); + rtnl_unlock(); break; default: --- a/net/ax25/ax25_dev.c +++ b/net/ax25/ax25_dev.c @@ -116,6 +116,7 @@ void ax25_dev_device_down(struct net_dev if ((s = ax25_dev_list) == ax25_dev) { ax25_dev_list = s->next; spin_unlock_bh(&ax25_dev_lock); + dev->ax25_ptr = NULL; dev_put(dev); kfree(ax25_dev); return; @@ -125,6 +126,7 @@ void ax25_dev_device_down(struct net_dev if (s->next == ax25_dev) { s->next = ax25_dev->next; spin_unlock_bh(&ax25_dev_lock); + dev->ax25_ptr = NULL; dev_put(dev); kfree(ax25_dev); return;