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 shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3A765C43217 for ; Thu, 13 Jan 2022 22:45:50 +0000 (UTC) Received: from localhost ([::1] helo=shelob.surriel.com) by shelob.surriel.com with esmtp (Exim 4.94.2) (envelope-from ) id 1n88q8-0000XU-6b; Thu, 13 Jan 2022 17:45:04 -0500 Received: from mail-pl1-x62a.google.com ([2607:f8b0:4864:20::62a]) by shelob.surriel.com with esmtps (TLS1.2) tls TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1n88q4-0000X8-Tf for kernelnewbies@kernelnewbies.org; Thu, 13 Jan 2022 17:45:00 -0500 Received: by mail-pl1-x62a.google.com with SMTP id n11so9716937plf.4 for ; Thu, 13 Jan 2022 14:44:59 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:reply-to:from:date:message-id :subject:to:cc; bh=kIvh3JTOv8scywQ2DWl9i63DFM9ehevQeBsnA55BZ3o=; b=WYK07QUKhJmq5sbACyXDjd8+m1O9U43fyvl5rI9w+bZYbrjbx6csUxdJiQSKBhtELp npFlvkzc1Qc98ug0BMxpk3ueN4npm4XfgQrZvGpLYe76atQTvE6HoBUQEzQD5lK+ykrd qY6VztcnaYNyywtUPtIJhGVf697W30ZxxVsT2fpOwDW4RlYkriUueDSH4FHi4xj/HP09 FHwYY2hvRIn3dqOdTpDlBu6tZHbk9Vf89F6Qph8RliyJt91S8/E1giaVsg3KBht0tTlg ZowEYSNWB7MVVgZyNS5viztI32w0ATRRkXvPwlrhXyApFLRwFy0f4ZGE9DDeOoLALt4x rznQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:reply-to :from:date:message-id:subject:to:cc; bh=kIvh3JTOv8scywQ2DWl9i63DFM9ehevQeBsnA55BZ3o=; b=XyL05wLMmblKHBuNyn9kJKL1t4xdzoGUTRVxycjowyqDZuOIHakVPaLkKmEt6L8DHe lZk6C+80qw1q9eLeVpLgYMxShUrmoskO/bH6zJ1MTlC97FZLKS1kIO/CmJkbAsxb5Wzx X0YudxvFXTtU3Ov13RwxqufXv2+8Q82Bh0jR0uY0KTcLMFOGoV4Kk7Lh4oK8bdZTBB9e th9sru6DyJQxbenZIQctck20ukB4W4BoNdMwhatsJ9AqmmqCn9bCbkT+uuLzx0mwK2nv Swx0J32/aGr/JtEMK4oTA8l6X2MQWv8QWWK2bWMvb5VuF+AnrZOV9wTtIlpYUXAnP6S1 e0vQ== X-Gm-Message-State: AOAM5301XeO4IwiqoPoi2wbPObEvDxrMWTkjH5AP0NfpwbuMg3+oN6gy 2LNzQxnzhI7yPGl3ahEKzavPSZbOZNagWuYtz63/oul+3Fc= X-Google-Smtp-Source: ABdhPJzt2DsTeHaoytmt1BYZWs21tqgWuYnzuF0Nazva4iukLTtju1XqTQ9tIuthjtfYysv4kL8rKWL/RsJqQqIec6k= X-Received: by 2002:a17:90a:df15:: with SMTP id gp21mr16993257pjb.108.1642113898634; Thu, 13 Jan 2022 14:44:58 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Jeffrey Walton Date: Thu, 13 Jan 2022 17:44:47 -0500 Message-ID: Subject: Re: How to disable address randomization ? To: admin LI Cc: kernelnewbies X-BeenThere: kernelnewbies@kernelnewbies.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Learn about the Linux kernel List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: noloader@gmail.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kernelnewbies-bounces@kernelnewbies.org On Thu, Jan 13, 2022 at 4:04 PM admin LI wrote: > > I'm developing a kernel module for an ARM machine, while debugging I found addresses > printed are all randomized and useless for debugging. > > To prove I was not crazy I wrote this small program: > > --------------------------------- > #include > #include > #include > #include > > MODULE_LICENSE("GPL"); > MODULE_AUTHOR("Somebody"); > MODULE_DESCRIPTION("A simple example Linux module."); > MODULE_VERSION("0.01"); > > static int __init example_init(void) { > uint32_t a; > uint32_t b; > uint32_t c; > uint8_t d[10]; > uint8_t *e; > > printk(KERN_INFO "Hello, World!\n"); > printk(KERN_INFO "&a %p\n",&a); > printk(KERN_INFO "&b %p\n",&b); > printk(KERN_INFO "&c %p\n",&c); > printk(KERN_INFO "&d %p\n",d); > printk(KERN_INFO "&d[0] %p\n",&d[0]); > printk(KERN_INFO "&d[1] %p\n",&d[1]); > > e = kmalloc(10, GFP_KERNEL); > printk(KERN_INFO "&e[0] %p\n",&e[0]); > printk(KERN_INFO "&e[1] %p\n",&e[1]); > > kfree(e); > > return 0; > } > > static void __exit example_exit(void) { > printk(KERN_INFO "Goodbye, World!\n"); > } > > module_init(example_init); > module_exit(example_exit); > --------------------------------- > And it gave me this output: > > Hello, World! > &a b3f9fa31 > &b 27e1c68a > &c da50d287 > &d 9f9aec2b > &d[0] 9f9aec2b > &d[1] cc627580 > &e[0] 98b8c9eb > &e[1] 45f248f8 > > Then I tested on my debian host machine which gave me the same kind of randomized addresses. > > When I search randomization the only thing I found is KASLR which I don't think is the same thing. I think something else may be going on, but I'll toss this out there in case it helps. In the past randomization was disabled by writing 0 to /proc/sys/kernel/randomize_va_space. Something like: sysctl -w kernel.randomize_va_space=0 To make it permanent, change it in /etc/sysctl.conf. Jeff _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies