From patchwork Fri May 20 02:31:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhang Xiaoxu X-Patchwork-Id: 12856195 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2CB30C433F5 for ; Fri, 20 May 2022 01:46:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344435AbiETBql (ORCPT ); Thu, 19 May 2022 21:46:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42854 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234339AbiETBqk (ORCPT ); Thu, 19 May 2022 21:46:40 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0E90F5DA4C for ; Thu, 19 May 2022 18:46:39 -0700 (PDT) Received: from dggpeml500023.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4L48gF3VmhzgYHy; Fri, 20 May 2022 09:45:13 +0800 (CST) Received: from localhost.localdomain (10.175.101.6) by dggpeml500023.china.huawei.com (7.185.36.114) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Fri, 20 May 2022 09:46:36 +0800 From: Zhang Xiaoxu To: , , , , , Subject: [PATCH] nfsd: Fix null-ptr-deref in nfsd_fill_super() Date: Fri, 20 May 2022 10:31:06 +0800 Message-ID: <20220520023106.6651-1-zhangxiaoxu5@huawei.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpeml500023.china.huawei.com (7.185.36.114) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org KASAN report null-ptr-deref as follows: BUG: KASAN: null-ptr-deref in nfsd_fill_super+0xc6/0xe0 [nfsd] Write of size 8 at addr 000000000000005d by task a.out/852 CPU: 7 PID: 852 Comm: a.out Not tainted 5.18.0-rc7-dirty #66 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1.fc33 04/01/2014 Call Trace: dump_stack_lvl+0x34/0x44 kasan_report+0xab/0x120 ? nfsd_mkdir+0x71/0x1c0 [nfsd] ? nfsd_fill_super+0xc6/0xe0 [nfsd] nfsd_fill_super+0xc6/0xe0 [nfsd] ? nfsd_mkdir+0x1c0/0x1c0 [nfsd] get_tree_keyed+0x8e/0x100 vfs_get_tree+0x41/0xf0 __do_sys_fsconfig+0x590/0x670 ? fscontext_read+0x180/0x180 ? anon_inode_getfd+0x4f/0x70 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae This can be reproduce by concurrent operations: 1. fsopen(nfsd)/fsconfig 2. insmod/rmmod nfsd Since the nfsd file system is registered before than nfsd_net allocated, the caller may get the file_system_type and use the nfsd_net before it allocated, then null-ptr-deref occured. So should allocate the nfsd_net firstly, other than register file system. Fixes: bd5ae9288d64 ("nfsd: register pernet ops last, unregister first") Cc: stable@kernel.org Signed-off-by: Zhang Xiaoxu --- fs/nfsd/nfsctl.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 16920e4512bd..e17100e90e19 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1535,20 +1535,20 @@ static int __init init_nfsd(void) retval = create_proc_exports_entry(); if (retval) goto out_free_lockd; - retval = register_filesystem(&nfsd_fs_type); - if (retval) - goto out_free_exports; retval = register_pernet_subsys(&nfsd_net_ops); if (retval < 0) - goto out_free_filesystem; + goto out_free_exports; retval = register_cld_notifier(); + if (retval) + goto out_free_subsys; + retval = register_filesystem(&nfsd_fs_type); if (retval) goto out_free_all; return 0; out_free_all: + unregister_cld_notifier(); +out_free_subsys: unregister_pernet_subsys(&nfsd_net_ops); -out_free_filesystem: - unregister_filesystem(&nfsd_fs_type); out_free_exports: remove_proc_entry("fs/nfs/exports", NULL); remove_proc_entry("fs/nfs", NULL); @@ -1566,6 +1566,7 @@ static int __init init_nfsd(void) static void __exit exit_nfsd(void) { + unregister_filesystem(&nfsd_fs_type); unregister_cld_notifier(); unregister_pernet_subsys(&nfsd_net_ops); nfsd_drc_slab_free(); @@ -1575,7 +1576,6 @@ static void __exit exit_nfsd(void) nfsd_lockd_shutdown(); nfsd4_free_slabs(); nfsd4_exit_pnfs(); - unregister_filesystem(&nfsd_fs_type); } MODULE_AUTHOR("Olaf Kirch ");