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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6326BC6FA82 for ; Tue, 13 Sep 2022 16:00:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234010AbiIMQA4 (ORCPT ); Tue, 13 Sep 2022 12:00:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235573AbiIMQAI (ORCPT ); Tue, 13 Sep 2022 12:00:08 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5854D956BC; Tue, 13 Sep 2022 07:58:27 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 914FC614EB; Tue, 13 Sep 2022 14:33:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 86939C433D6; Tue, 13 Sep 2022 14:33:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663079593; bh=JBXl8o5PzldYcwYjx7aTRdDFZwXaECqL96GgEg8CeJY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=muZ/cOFDI7NSa9PYHpAgvLvt/eQV1jg5szRSoGMHJXrJXDYPMTwU3gmq6BkRbcgG9 U6QgjoZXr/laKwXy4wHKcyrnowKwHqLY/fzEYoyMcGYAiJPtAf397CP7v0ji0gsd/l tnQ6ER2SN9fhu6Sf8S9DiWPacxFswdV8yX1t7TLE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, stable , Kuyo Chang Subject: [PATCH 4.19 61/79] debugfs: add debugfs_lookup_and_remove() Date: Tue, 13 Sep 2022 16:07:19 +0200 Message-Id: <20220913140351.839626204@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220913140348.835121645@linuxfoundation.org> References: <20220913140348.835121645@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Greg Kroah-Hartman commit dec9b2f1e0455a151a7293c367da22ab973f713e upstream. There is a very common pattern of using debugfs_remove(debufs_lookup(..)) which results in a dentry leak of the dentry that was looked up. Instead of having to open-code the correct pattern of calling dput() on the dentry, create debugfs_lookup_and_remove() to handle this pattern automatically and properly without any memory leaks. Cc: stable Reported-by: Kuyo Chang Tested-by: Kuyo Chang Link: https://lore.kernel.org/r/YxIaQ8cSinDR881k@kroah.com Signed-off-by: Greg Kroah-Hartman --- fs/debugfs/inode.c | 22 ++++++++++++++++++++++ include/linux/debugfs.h | 6 ++++++ 2 files changed, 28 insertions(+) --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -767,6 +767,28 @@ void debugfs_remove_recursive(struct den EXPORT_SYMBOL_GPL(debugfs_remove_recursive); /** + * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it + * @name: a pointer to a string containing the name of the item to look up. + * @parent: a pointer to the parent dentry of the item. + * + * This is the equlivant of doing something like + * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting + * handled for the directory being looked up. + */ +void debugfs_lookup_and_remove(const char *name, struct dentry *parent) +{ + struct dentry *dentry; + + dentry = debugfs_lookup(name, parent); + if (!dentry) + return; + + debugfs_remove(dentry); + dput(dentry); +} +EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove); + +/** * debugfs_rename - rename a file/directory in the debugfs filesystem * @old_dir: a pointer to the parent dentry for the renamed object. This * should be a directory dentry. --- a/include/linux/debugfs.h +++ b/include/linux/debugfs.h @@ -85,6 +85,8 @@ struct dentry *debugfs_create_automount( void debugfs_remove(struct dentry *dentry); void debugfs_remove_recursive(struct dentry *dentry); +void debugfs_lookup_and_remove(const char *name, struct dentry *parent); + const struct file_operations *debugfs_real_fops(const struct file *filp); int debugfs_file_get(struct dentry *dentry); @@ -217,6 +219,10 @@ static inline void debugfs_remove(struct static inline void debugfs_remove_recursive(struct dentry *dentry) { } +static inline void debugfs_lookup_and_remove(const char *name, + struct dentry *parent) +{ } + const struct file_operations *debugfs_real_fops(const struct file *filp); static inline int debugfs_file_get(struct dentry *dentry)