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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 65A84C43381 for ; Thu, 28 Feb 2019 15:31:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2431F20C01 for ; Thu, 28 Feb 2019 15:31:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551367916; bh=1IIk6XIx7k+qSdumUby1AWzknyn7Bvt2OsBKS3zjzrM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=KdxziVI9pkiSVO/2KIgPewAGYLBvh1TMC/mE+QKwR39qE4OUkFksH8/Ez1IPVICBm aqubumdsMkrwZvAt988AGSoZVCMHjJfkl0mYdzDIXfL4wKLeNO/xIvETG0t8wSvTrN sO5A0z4PzRMuJWQUHW39LbZ47EJD8+LMLq4lOmg4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388185AbfB1Pbz (ORCPT ); Thu, 28 Feb 2019 10:31:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:41592 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387444AbfB1PJH (ORCPT ); Thu, 28 Feb 2019 10:09:07 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B7629218CD; Thu, 28 Feb 2019 15:09:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551366546; bh=1IIk6XIx7k+qSdumUby1AWzknyn7Bvt2OsBKS3zjzrM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uWH8rPGmY2g6vZceNQa1GTW6WIbGe/uuLCjt977mNqBCWOkQs+eHQqM9Wq/xLQcwx pnsiSAlxfKyvaBMdZZs6fVzHPVRJb6TcAvJTeqs93ggydJ0Ugq2NH9g3MqMbL28/kX o1viGmb4mEX9QdPJWD0smDQRdbvuFEH0gAo7IJGw= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Sasha Levin Subject: [PATCH AUTOSEL 4.20 34/81] debugfs: return error values, not NULL Date: Thu, 28 Feb 2019 10:07:26 -0500 Message-Id: <20190228150813.10256-34-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190228150813.10256-1-sashal@kernel.org> References: <20190228150813.10256-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Greg Kroah-Hartman [ Upstream commit ff9fb72bc07705c00795ca48631f7fffe24d2c6b ] When an error happens, debugfs should return an error pointer value, not NULL. This will prevent the totally theoretical error where a debugfs call fails due to lack of memory, returning NULL, and that dentry value is then passed to another debugfs call, which would end up succeeding, creating a file at the root of the debugfs tree, but would then be impossible to remove (because you can not remove the directory NULL). So, to make everyone happy, always return errors, this makes the users of debugfs much simpler (they do not have to ever check the return value), and everyone can rest easy. Reported-by: Gary R Hook Reported-by: Heiko Carstens Reported-by: Masami Hiramatsu Reported-by: Michal Hocko Reported-by: Sebastian Andrzej Siewior Reported-by: Ulf Hansson Reviewed-by: Masami Hiramatsu Reviewed-by: Sebastian Andrzej Siewior Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- fs/debugfs/inode.c | 39 ++++++++++++++++++++++----------------- 1 file changed, 22 insertions(+), 17 deletions(-) diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c index 41ef452c1fcfb..b16f8035b1af7 100644 --- a/fs/debugfs/inode.c +++ b/fs/debugfs/inode.c @@ -254,8 +254,8 @@ MODULE_ALIAS_FS("debugfs"); * @parent: a pointer to the parent dentry of the file. * * This function will return a pointer to a dentry if it succeeds. If the file - * doesn't exist or an error occurs, %NULL will be returned. The returned - * dentry must be passed to dput() when it is no longer needed. + * doesn't exist or an error occurs, %ERR_PTR(-ERROR) will be returned. The + * returned dentry must be passed to dput() when it is no longer needed. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. @@ -265,17 +265,17 @@ struct dentry *debugfs_lookup(const char *name, struct dentry *parent) struct dentry *dentry; if (IS_ERR(parent)) - return NULL; + return parent; if (!parent) parent = debugfs_mount->mnt_root; dentry = lookup_one_len_unlocked(name, parent, strlen(name)); if (IS_ERR(dentry)) - return NULL; + return dentry; if (!d_really_is_positive(dentry)) { dput(dentry); - return NULL; + return ERR_PTR(-EINVAL); } return dentry; } @@ -324,7 +324,7 @@ static struct dentry *failed_creating(struct dentry *dentry) inode_unlock(d_inode(dentry->d_parent)); dput(dentry); simple_release_fs(&debugfs_mount, &debugfs_mount_count); - return NULL; + return ERR_PTR(-ENOMEM); } static struct dentry *end_creating(struct dentry *dentry) @@ -347,7 +347,7 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode, dentry = start_creating(name, parent); if (IS_ERR(dentry)) - return NULL; + return dentry; inode = debugfs_get_inode(dentry->d_sb); if (unlikely(!inode)) @@ -386,7 +386,8 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode, * This function will return a pointer to a dentry if it succeeds. This * pointer must be passed to the debugfs_remove() function when the file is * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. + * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be + * returned. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. @@ -464,7 +465,8 @@ EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe); * This function will return a pointer to a dentry if it succeeds. This * pointer must be passed to the debugfs_remove() function when the file is * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. + * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be + * returned. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. @@ -495,7 +497,8 @@ EXPORT_SYMBOL_GPL(debugfs_create_file_size); * This function will return a pointer to a dentry if it succeeds. This * pointer must be passed to the debugfs_remove() function when the file is * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. + * you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) will be + * returned. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. @@ -506,7 +509,7 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) struct inode *inode; if (IS_ERR(dentry)) - return NULL; + return dentry; inode = debugfs_get_inode(dentry->d_sb); if (unlikely(!inode)) @@ -545,7 +548,7 @@ struct dentry *debugfs_create_automount(const char *name, struct inode *inode; if (IS_ERR(dentry)) - return NULL; + return dentry; inode = debugfs_get_inode(dentry->d_sb); if (unlikely(!inode)) @@ -581,8 +584,8 @@ EXPORT_SYMBOL(debugfs_create_automount); * This function will return a pointer to a dentry if it succeeds. This * pointer must be passed to the debugfs_remove() function when the symbolic * link is to be removed (no automatic cleanup happens if your module is - * unloaded, you are responsible here.) If an error occurs, %NULL will be - * returned. + * unloaded, you are responsible here.) If an error occurs, %ERR_PTR(-ERROR) + * will be returned. * * If debugfs is not enabled in the kernel, the value -%ENODEV will be * returned. @@ -594,12 +597,12 @@ struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent, struct inode *inode; char *link = kstrdup(target, GFP_KERNEL); if (!link) - return NULL; + return ERR_PTR(-ENOMEM); dentry = start_creating(name, parent); if (IS_ERR(dentry)) { kfree(link); - return NULL; + return dentry; } inode = debugfs_get_inode(dentry->d_sb); @@ -827,7 +830,9 @@ struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry, if (dentry && !IS_ERR(dentry)) dput(dentry); unlock_rename(new_dir, old_dir); - return NULL; + if (IS_ERR(dentry)) + return dentry; + return ERR_PTR(-EINVAL); } EXPORT_SYMBOL_GPL(debugfs_rename); -- 2.19.1