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=-10.5 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=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 EA12BC43387 for ; Fri, 11 Jan 2019 15:13:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BB6042177B for ; Fri, 11 Jan 2019 15:13:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547219627; bh=pdS8msKkP7S5fvCe6Kx6fer6qbBpdqhXPLSeXCx+FsA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OWKf0wC9i2GwRDxOgO87iCktVPVHI0H0h8+0Vke6jut01qegM7N0R/fb6TYqY0/Dn XfSpImoORpxGtKBFrxCUFg7Fjuy86dErLAc2fq8azh7t1M9ZK4IE5+3DzXRLFoXOJW mUAj8gJZFLr1+lH/KlyHbmhrA2Di6ZlJOz/O4ztA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733178AbfAKPNk (ORCPT ); Fri, 11 Jan 2019 10:13:40 -0500 Received: from mail.kernel.org ([198.145.29.99]:58638 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733137AbfAKOOr (ORCPT ); Fri, 11 Jan 2019 09:14:47 -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 130072177B; Fri, 11 Jan 2019 14:14:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547216086; bh=pdS8msKkP7S5fvCe6Kx6fer6qbBpdqhXPLSeXCx+FsA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ct3HemASYc2I95hAe2emfNsxDeaGCJKXrcHXeSL5PtdWRH0U2W8Zhs15KaIryCIv8 H7OriiQ2MWJHGTxdXjNpV63ZArHnFzAbF33GEYMBLZa4wgrQ28dqCnuzGiB0lo+Lnw DwEQvMKkKRgxNNeRBiPbMiDDGhSCtd7vk9J4H17g= 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 3.18 08/47] ax25: fix a use-after-free in ax25_fillin_cb() Date: Fri, 11 Jan 2019 15:07:53 +0100 Message-Id: <20190111130957.183353754@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190111130956.170952125@linuxfoundation.org> References: <20190111130956.170952125@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: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 3.18-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 @@ -655,15 +655,22 @@ 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;