From nobody Mon Sep 8 08:50:01 2025 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 88245C6FA82 for ; Tue, 13 Sep 2022 15:20:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236025AbiIMPUp (ORCPT ); Tue, 13 Sep 2022 11:20:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57158 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235681AbiIMPSI (ORCPT ); Tue, 13 Sep 2022 11:18:08 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FC1357224; Tue, 13 Sep 2022 07:35:00 -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 F3759614AA; Tue, 13 Sep 2022 14:28:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 156B7C433D6; Tue, 13 Sep 2022 14:28:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663079303; bh=KunAitdqsNAr8OHLeGsc+rfXUt+DkWrQu4cvq4FpV7U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QeRW3xgsmkvXAYd24nHJL8EjDeqDGyI5y+sAgCxz5YlPa3/ekQfn4td5A3e8IYkFw WulLqZGLVf2Ys7ALoxRyA33L6N3j1ydRSRhFbU9cTqrFR7OYiI4PUymafh0nULM/e7 wf/B1tt5nV0OQxCVlY+gt0fT8HILshBlSih///iw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, stable , Kuyo Chang Subject: [PATCH 5.4 081/108] debugfs: add debugfs_lookup_and_remove() Date: Tue, 13 Sep 2022 16:06:52 +0200 Message-Id: <20220913140357.110806115@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220913140353.549108748@linuxfoundation.org> References: <20220913140353.549108748@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 @@ -743,6 +743,28 @@ void debugfs_remove(struct dentry *dentr EXPORT_SYMBOL_GPL(debugfs_remove); =20 /** + * 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 counti= ng + * handled for the directory being looked up. + */ +void debugfs_lookup_and_remove(const char *name, struct dentry *parent) +{ + struct dentry *dentry; + + dentry =3D debugfs_lookup(name, parent); + if (!dentry) + return; + + debugfs_remove(dentry); + dput(dentry); +} +EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove); + +/** * debugfs_remove_recursive - recursively removes a directory * @dentry: a pointer to a the dentry of the directory to be removed. If = this * parameter is NULL or an error value, nothing will be done. --- 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); =20 +void debugfs_lookup_and_remove(const char *name, struct dentry *parent); + const struct file_operations *debugfs_real_fops(const struct file *filp); =20 int debugfs_file_get(struct dentry *dentry); @@ -216,6 +218,10 @@ static inline void debugfs_remove(struct static inline void debugfs_remove_recursive(struct dentry *dentry) { } =20 +static inline void debugfs_lookup_and_remove(const char *name, + struct dentry *parent) +{ } + const struct file_operations *debugfs_real_fops(const struct file *filp); =20 static inline int debugfs_file_get(struct dentry *dentry)