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 B7C56C04E53 for ; Wed, 15 May 2019 12:10:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7FE6220657 for ; Wed, 15 May 2019 12:10:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557922255; bh=pmDpI0mOfPRu39fWnUV4I/+4ZjVdkBEGEqtqWuIjavQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=moa48GosdtHton0S1ByqMg/NJk2sIJwDUATqH8SRaOzx3fG2PeaWsF3fLrils+CIS rMTzhM6+ArghobPAyZgxun/KrF0kx//2I9gyofsJrQ1/JEFX/9QwQJ4IkKtGvVG0e2 LeH9824WmyxvYmpFFXIpackk5lPPGzBETdGB8ZPk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728871AbfEOMKy (ORCPT ); Wed, 15 May 2019 08:10:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:38182 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728532AbfEOLHA (ORCPT ); Wed, 15 May 2019 07:07:00 -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 6FE5E21734; Wed, 15 May 2019 11:06:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557918419; bh=pmDpI0mOfPRu39fWnUV4I/+4ZjVdkBEGEqtqWuIjavQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0wym0iVvw9U2XZxjHTZZicNsqRkLQznxNl89y1QRlMIozlPLir8YzSbi4A4ZN/fQ+ tjD8Xv8KLTUaoKRzgGmIA+7rpib1P1bcwZpuiZfqu0UCIuZiGTRrUqKeQwNhbawBtH g6JNHrU8Gjt1Y5dNRPsOjNqX8Zu1bEQE7ijzWTR8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Al Viro , Sasha Levin Subject: [PATCH 4.4 125/266] debugfs: fix use-after-free on symlink traversal Date: Wed, 15 May 2019 12:53:52 +0200 Message-Id: <20190515090727.007426951@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190515090722.696531131@linuxfoundation.org> References: <20190515090722.696531131@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 93b919da64c15b90953f96a536e5e61df896ca57 ] symlink body shouldn't be freed without an RCU delay. Switch debugfs to ->destroy_inode() and use of call_rcu(); free both the inode and symlink body in the callback. Similar to solution for bpf, only here it's even more obvious that ->evict_inode() can be dropped. Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- fs/debugfs/inode.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index 22fe11baef2b..3530e1c3ff56 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -164,19 +164,24 @@ static int debugfs_show_options(struct seq_file *m, struct dentry *root) return 0; } -static void debugfs_evict_inode(struct inode *inode) +static void debugfs_i_callback(struct rcu_head *head) { - truncate_inode_pages_final(&inode->i_data); - clear_inode(inode); + struct inode *inode = container_of(head, struct inode, i_rcu); if (S_ISLNK(inode->i_mode)) kfree(inode->i_link); + free_inode_nonrcu(inode); +} + +static void debugfs_destroy_inode(struct inode *inode) +{ + call_rcu(&inode->i_rcu, debugfs_i_callback); } static const struct super_operations debugfs_super_operations = { .statfs = simple_statfs, .remount_fs = debugfs_remount, .show_options = debugfs_show_options, - .evict_inode = debugfs_evict_inode, + .destroy_inode = debugfs_destroy_inode, }; static struct vfsmount *debugfs_automount(struct path *path) -- 2.20.1