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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 38F0FC433EF for ; Mon, 15 Nov 2021 18:12:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2555A63486 for ; Mon, 15 Nov 2021 18:12:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239747AbhKOSPL (ORCPT ); Mon, 15 Nov 2021 13:15:11 -0500 Received: from mail.kernel.org ([198.145.29.99]:50902 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237976AbhKOR2a (ORCPT ); Mon, 15 Nov 2021 12:28:30 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4488F6326D; Mon, 15 Nov 2021 17:18:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1636996731; bh=EhuQGIfKx2K89QJ7yeJ7Nto+4H77n+aK0HPCrsRD5rE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rkxgvJmw1eW/xDzmqUb564XYjiypcfPB6ot5WvEb60TVGp3VsympkyLCZRglYtos2 9g945VkYq3IfjDjqMI+VnB+wAotr6oRxoNui5hOY8mFsLgqA++JHS7JDycTSSgujr5 OhPyslm9si/9HS5HPFVHHVElEttsXxJTLoZJjISA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Punit Agrawal , Masami Hiramatsu , "Steven Rostedt (VMware)" , Sasha Levin Subject: [PATCH 5.4 205/355] kprobes: Do not use local variable when creating debugfs file Date: Mon, 15 Nov 2021 18:02:09 +0100 Message-Id: <20211115165320.394574008@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211115165313.549179499@linuxfoundation.org> References: <20211115165313.549179499@linuxfoundation.org> User-Agent: quilt/0.66 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: Punit Agrawal [ Upstream commit 8f7262cd66699a4b02eb7549b35c81b2116aad95 ] debugfs_create_file() takes a pointer argument that can be used during file operation callbacks (accessible via i_private in the inode structure). An obvious requirement is for the pointer to refer to valid memory when used. When creating the debugfs file to dynamically enable / disable kprobes, a pointer to local variable is passed to debugfs_create_file(); which will go out of scope when the init function returns. The reason this hasn't triggered random memory corruption is because the pointer is not accessed during the debugfs file callbacks. Since the enabled state is managed by the kprobes_all_disabled global variable, the local variable is not needed. Fix the incorrect (and unnecessary) usage of local variable during debugfs_file_create() by passing NULL instead. Link: https://lkml.kernel.org/r/163163031686.489837.4476867635937014973.stgit@devnote2 Fixes: bf8f6e5b3e51 ("Kprobes: The ON/OFF knob thru debugfs") Signed-off-by: Punit Agrawal Acked-by: Masami Hiramatsu Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Sasha Levin --- kernel/kprobes.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index a7812c115e487..1668439b269d3 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2712,14 +2712,13 @@ static const struct file_operations fops_kp = { static int __init debugfs_kprobe_init(void) { struct dentry *dir; - unsigned int value = 1; dir = debugfs_create_dir("kprobes", NULL); debugfs_create_file("list", 0400, dir, NULL, &debugfs_kprobes_operations); - debugfs_create_file("enabled", 0600, dir, &value, &fops_kp); + debugfs_create_file("enabled", 0600, dir, NULL, &fops_kp); debugfs_create_file("blacklist", 0400, dir, NULL, &debugfs_kprobe_blacklist_ops); -- 2.33.0