From patchwork Tue Sep 14 14:38:37 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Masami Hiramatsu (Google)" X-Patchwork-Id: 12493671 X-Patchwork-Delegate: bpf@iogearbox.net 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 5F415C433EF for ; Tue, 14 Sep 2021 14:38:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 46F73610D1 for ; Tue, 14 Sep 2021 14:38:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233687AbhINOj7 (ORCPT ); Tue, 14 Sep 2021 10:39:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:60920 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233614AbhINOj6 (ORCPT ); Tue, 14 Sep 2021 10:39:58 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6CAC1610CE; Tue, 14 Sep 2021 14:38:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631630321; bh=4xQiQDDV7nXJL8Xan+15i4FwcNOTqTiYzYCdCLjItZQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N5F7dsm3oC3uWyspwozTKIHTqoDUSpeWzd2cFIzjDhYfwuHRmblgxYcBS5r4Q0hms fV6v7crr6GMxQwrgBCCrY8zspDHYWnYlynmfEFDiFfSdHSuYNpSfYCIPmyUL6uVj6C v6g9TBqpQQk24LXe4gWje5oEYx9+og5T5QUDYso7jq/CcYRb1pWEWy6YMhY1nlj83x pbsBqG8FU5CXWkJjtxzRvRL5FT2Eem287aIg7Tz9NYhMLpoWEd8NjMBExtzw0PW4tf 9jbYizbkmoOzNSXoB+A1KHa+ItddVhB5fNLXLaNScI8Vjydfb90NMdcNPaLrRPNzxF O6FpkVf8diEJQ== From: Masami Hiramatsu To: Steven Rostedt , Josh Poimboeuf , Ingo Molnar Cc: X86 ML , Masami Hiramatsu , Daniel Xu , linux-kernel@vger.kernel.org, bpf@vger.kernel.org, kuba@kernel.org, mingo@redhat.com, ast@kernel.org, Thomas Gleixner , Borislav Petkov , Peter Zijlstra , kernel-team@fb.com, yhs@fb.com, linux-ia64@vger.kernel.org, Abhishek Sagar , Andrii Nakryiko , Paul McKenney Subject: [PATCH -tip v11 01/27] kprobes: Do not use local variable when creating debugfs file Date: Tue, 14 Sep 2021 23:38:37 +0900 Message-Id: <163163031686.489837.4476867635937014973.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <163163030719.489837.2236069935502195491.stgit@devnote2> References: <163163030719.489837.2236069935502195491.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org From: Punit Agrawal 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. Fixes: bf8f6e5b3e51 ("Kprobes: The ON/OFF knob thru debugfs") Signed-off-by: Punit Agrawal Acked-by: Masami Hiramatsu Signed-off-by: Masami Hiramatsu --- kernel/kprobes.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 790a573bbe00..1cf8bca1ea86 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2809,13 +2809,12 @@ 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, &kprobes_fops); - 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, &kprobe_blacklist_fops);