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=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,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 17F46C28CC2 for ; Thu, 30 May 2019 04:13:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E6672251FA for ; Thu, 30 May 2019 04:13:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559189633; bh=DDAiTRqEGOZMR5wKbJ4tM+vT0aH2qQvHbBxCDs12tLQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ywqOvIQHTAOlZKGXpGX254FDijjsAJbuiEdaA8XfP/78SQiaNVDsPN8o7vQXHyTrM 4dV4+559rX893VkO+GjztuBkP/Rg8V56IqmzxrjkMmFr8DEqfCD/nm4v/1RXx8wdpA /pTQY7JXKjTPiJ5ZhbVjSr8qOj/7s/3adH67s/yE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727411AbfE3ENv (ORCPT ); Thu, 30 May 2019 00:13:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:41614 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730651AbfE3DQT (ORCPT ); Wed, 29 May 2019 23:16:19 -0400 Received: from localhost (ip67-88-213-2.z213-88-67.customer.algx.net [67.88.213.2]) (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 550D2245E4; Thu, 30 May 2019 03:16:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559186179; bh=DDAiTRqEGOZMR5wKbJ4tM+vT0aH2qQvHbBxCDs12tLQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QeYT+3GXKPX8yDQjxW/657gWtYqckr2gxEJVbKq/DQN/52LqS5zuOtNk957L8Yu6Z GVYWULsdwR0Mi2TBgwRU46XxDkN1BW3vhGmqcz89FpUYPmgzgg90UqNdh8BAfeFSb5 1ReOgx4zy/d1lSsQnOXGxHIz2PEt1WM+z85UcK5g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Amir Goldstein , syzbot+2a73a6ea9507b7112141@syzkaller.appspotmail.com, Al Viro Subject: [PATCH 4.19 042/276] acct_on(): dont mess with freeze protection Date: Wed, 29 May 2019 20:03:20 -0700 Message-Id: <20190530030527.049164563@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190530030523.133519668@linuxfoundation.org> References: <20190530030523.133519668@linuxfoundation.org> User-Agent: quilt/0.66 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 From: Al Viro commit 9419a3191dcb27f24478d288abaab697228d28e6 upstream. What happens there is that we are replacing file->path.mnt of a file we'd just opened with a clone and we need the write count contribution to be transferred from original mount to new one. That's it. We do *NOT* want any kind of freeze protection for the duration of switchover. IOW, we should just use __mnt_{want,drop}_write() for that switchover; no need to bother with mnt_{want,drop}_write() there. Tested-by: Amir Goldstein Reported-by: syzbot+2a73a6ea9507b7112141@syzkaller.appspotmail.com Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/internal.h | 2 -- include/linux/mount.h | 2 ++ kernel/acct.c | 4 ++-- 3 files changed, 4 insertions(+), 4 deletions(-) --- a/fs/internal.h +++ b/fs/internal.h @@ -80,9 +80,7 @@ extern int sb_prepare_remount_readonly(s extern void __init mnt_init(void); -extern int __mnt_want_write(struct vfsmount *); extern int __mnt_want_write_file(struct file *); -extern void __mnt_drop_write(struct vfsmount *); extern void __mnt_drop_write_file(struct file *); /* --- a/include/linux/mount.h +++ b/include/linux/mount.h @@ -86,6 +86,8 @@ extern bool mnt_may_suid(struct vfsmount struct path; extern struct vfsmount *clone_private_mount(const struct path *path); +extern int __mnt_want_write(struct vfsmount *); +extern void __mnt_drop_write(struct vfsmount *); struct file_system_type; extern struct vfsmount *vfs_kern_mount(struct file_system_type *type, --- a/kernel/acct.c +++ b/kernel/acct.c @@ -227,7 +227,7 @@ static int acct_on(struct filename *path filp_close(file, NULL); return PTR_ERR(internal); } - err = mnt_want_write(internal); + err = __mnt_want_write(internal); if (err) { mntput(internal); kfree(acct); @@ -252,7 +252,7 @@ static int acct_on(struct filename *path old = xchg(&ns->bacct, &acct->pin); mutex_unlock(&acct->lock); pin_kill(old); - mnt_drop_write(mnt); + __mnt_drop_write(mnt); mntput(mnt); return 0; }