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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 E3743C10F0E for ; Mon, 15 Apr 2019 19:05:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD59920880 for ; Mon, 15 Apr 2019 19:05:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555355126; bh=XIx9ARAKjIZ9JLOSw4XBCYpzVv7FyVXP5tEeOMQhOMY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=1yZXiiDjLQ3ug1u6jugJHrDhGFZfq5j0yaPUa0srMCbEoDELIVQp+nUJlrUH38hI7 z73mCCj0viBfP3YwaROJnHNu9QEgfn0et/UiHc+/iQFGLFXXv0Zzz32J39udhP7s92 /7wGBmg4pygiRzEkAjnVkCeVIeaCWMRyDgq3tWPY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729717AbfDOTFZ (ORCPT ); Mon, 15 Apr 2019 15:05:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:38904 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729158AbfDOTFR (ORCPT ); Mon, 15 Apr 2019 15:05:17 -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 251092087C; Mon, 15 Apr 2019 19:05:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555355116; bh=XIx9ARAKjIZ9JLOSw4XBCYpzVv7FyVXP5tEeOMQhOMY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E7NMQEjUh7BYYeyTTrnk4xNKfDEMWo2Tq3NMI0Ldl8DHzukvBhmiaTeZZuVcjcgXN H+XEdOnU4DyK4GMoJKo2jSr5oYvnQEYCIcBkjBEi4tcUpHGhpmLByPRpdi9D3BKb+1 ujRe1FKyBTY55buQ5ylXUQnVtPz54ZxAed9PTmt8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michal Kubecek , Jiri Slaby , "David S. Miller" , Sasha Levin Subject: [PATCH 4.19 009/101] kcm: switch order of device registration to fix a crash Date: Mon, 15 Apr 2019 20:58:07 +0200 Message-Id: <20190415183740.861754206@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190415183740.341577907@linuxfoundation.org> References: <20190415183740.341577907@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 3c446e6f96997f2a95bf0037ef463802162d2323 ] When kcm is loaded while many processes try to create a KCM socket, a crash occurs: BUG: unable to handle kernel NULL pointer dereference at 000000000000000e IP: mutex_lock+0x27/0x40 kernel/locking/mutex.c:240 PGD 8000000016ef2067 P4D 8000000016ef2067 PUD 3d6e9067 PMD 0 Oops: 0002 [#1] SMP KASAN PTI CPU: 0 PID: 7005 Comm: syz-executor.5 Not tainted 4.12.14-396-default #1 SLE15-SP1 (unreleased) RIP: 0010:mutex_lock+0x27/0x40 kernel/locking/mutex.c:240 RSP: 0018:ffff88000d487a00 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 000000000000000e RCX: 1ffff100082b0719 ... CR2: 000000000000000e CR3: 000000004b1bc003 CR4: 0000000000060ef0 Call Trace: kcm_create+0x600/0xbf0 [kcm] __sock_create+0x324/0x750 net/socket.c:1272 ... This is due to race between sock_create and unfinished register_pernet_device. kcm_create tries to do "net_generic(net, kcm_net_id)". but kcm_net_id is not initialized yet. So switch the order of the two to close the race. This can be reproduced with mutiple processes doing socket(PF_KCM, ...) and one process doing module removal. Fixes: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module") Reviewed-by: Michal Kubecek Signed-off-by: Jiri Slaby Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/kcm/kcmsock.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c index 571d824e4e24..b919db02c7f9 100644 --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -2054,14 +2054,14 @@ static int __init kcm_init(void) if (err) goto fail; - err = sock_register(&kcm_family_ops); - if (err) - goto sock_register_fail; - err = register_pernet_device(&kcm_net_ops); if (err) goto net_ops_fail; + err = sock_register(&kcm_family_ops); + if (err) + goto sock_register_fail; + err = kcm_proc_init(); if (err) goto proc_init_fail; @@ -2069,12 +2069,12 @@ static int __init kcm_init(void) return 0; proc_init_fail: - unregister_pernet_device(&kcm_net_ops); - -net_ops_fail: sock_unregister(PF_KCM); sock_register_fail: + unregister_pernet_device(&kcm_net_ops); + +net_ops_fail: proto_unregister(&kcm_proto); fail: @@ -2090,8 +2090,8 @@ static int __init kcm_init(void) static void __exit kcm_exit(void) { kcm_proc_exit(); - unregister_pernet_device(&kcm_net_ops); sock_unregister(PF_KCM); + unregister_pernet_device(&kcm_net_ops); proto_unregister(&kcm_proto); destroy_workqueue(kcm_wq); -- 2.19.1