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=-11.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 11FF6C433E0 for ; Wed, 10 Jun 2020 21:50:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BFECE20656 for ; Wed, 10 Jun 2020 21:50:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726454AbgFJVuA (ORCPT ); Wed, 10 Jun 2020 17:50:00 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:42744 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726276AbgFJVt7 (ORCPT ); Wed, 10 Jun 2020 17:49:59 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]) by out01.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jj8be-00023d-AD; Wed, 10 Jun 2020 15:49:58 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1jj8bd-0000iK-IJ; Wed, 10 Jun 2020 15:49:58 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Linus Torvalds Cc: , Alexey Gladkov References: <875zc8kxyg.fsf@x220.int.ebiederm.org> Date: Wed, 10 Jun 2020 16:45:50 -0500 In-Reply-To: <875zc8kxyg.fsf@x220.int.ebiederm.org> (Eric W. Biederman's message of "Wed, 03 Jun 2020 09:47:51 -0500") Message-ID: <87zh9atx0x.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1jj8bd-0000iK-IJ;;;mid=<87zh9atx0x.fsf@x220.int.ebiederm.org>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX18RZcpIlb84vyLBuxdhHPmRMik2Wka0qQo= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [GIT PULL] proc fixes for v5.8-rc1 X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Please pull the proc-linus branch from the git tree: git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git proc-linus HEAD: 058f2e4da79b23afb56ce3d03d907d6cdd36f2b8 proc: s_fs_info may be NULL when proc_kill_sb is called Syzbot found a NULL pointer dereference if kzalloc of proc's s_fs_info fails. The fix is the patch below. --- From: Alexey Gladkov Date: Wed, 10 Jun 2020 20:35:49 +0200 Subject: [PATCH] proc: s_fs_info may be NULL when proc_kill_sb is called syzbot found that proc_fill_super() fails before filling up sb->s_fs_info, deactivate_locked_super() will be called and sb->s_fs_info will be NULL. The proc_kill_sb() does not expect fs_info to be NULL which is wrong. Link: https://lore.kernel.org/lkml/0000000000002d7ca605a7b8b1c5@google.com Reported-by: syzbot+4abac52934a48af5ff19@syzkaller.appspotmail.com Fixes: fa10fed30f25 ("proc: allow to mount many instances of proc in one pid namespace") Signed-off-by: Alexey Gladkov Signed-off-by: Eric W. Biederman --- fs/proc/root.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/fs/proc/root.c b/fs/proc/root.c index ffebed1999e5..5e444d4f9717 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -264,11 +264,13 @@ static void proc_kill_sb(struct super_block *sb) { struct proc_fs_info *fs_info = proc_sb_info(sb); - if (fs_info->proc_self) - dput(fs_info->proc_self); + if (!fs_info) { + kill_anon_super(sb); + return; + } - if (fs_info->proc_thread_self) - dput(fs_info->proc_thread_self); + dput(fs_info->proc_self); + dput(fs_info->proc_thread_self); kill_anon_super(sb); put_pid_ns(fs_info->pid_ns); -- 2.20.1