Re: [PATCH 3/3] [v4] lib/vsprintf: no_hash_pointers prints all addresses as unhashed

From: Matthew Wilcox <willy@infradead.org>
To: Marco Elver <elver@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Vlastimil Babka <vbabka@suse.cz>, Petr Mladek <pmladek@suse.com>,
	Timur Tabi <timur@kernel.org>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	roman.fietze@magna.com, Kees Cook <keescook@chromium.org>,
	John Ogness <john.ogness@linutronix.de>,
	Akinobu Mita <akinobu.mita@gmail.com>,
	Alexander Potapenko <glider@google.com>,
	Andrey Konovalov <andreyknvl@google.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Pavel Machek <pavel@ucw.cz>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>
Subject: Re: [PATCH 3/3] [v4] lib/vsprintf: no_hash_pointers prints all addresses as unhashed
Date: Tue, 2 Mar 2021 14:35:16 +0000	[thread overview]
Message-ID: <20210302143516.GY2723601@casper.infradead.org> (raw)
In-Reply-To: <YD5LKqtSz5r1Xp7B@elver.google.com>

On Tue, Mar 02, 2021 at 03:26:50PM +0100, Marco Elver wrote:
> +static const char no_hash_pointers_warning[9][55] __initconst = {
> +	"******************************************************",
> +	"   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   ",
> +	"                                                      ",
> +	" This system shows unhashed kernel memory addresses   ",
> +	" via the console, logs, and other interfaces. This    ",
> +	" might reduce the security of your system.            ",
> +	" If you see this message and you are not debugging    ",
> +	" the kernel, report this immediately to your system   ",
> +	" administrator!                                       ",
> +};
> +
>  static int __init no_hash_pointers_enable(char *str)
>  {
> +	const int lines[] = { 0, 1, 2, 3, 4, 5, 2, 6, 7, 8, 2, 1, 0 };
> +	int i;
> +
>  	no_hash_pointers = true;
>  
> -	pr_warn("**********************************************************\n");
> -	pr_warn("**   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **\n");
> -	pr_warn("**                                                      **\n");
> -	pr_warn("** This system shows unhashed kernel memory addresses   **\n");
> -	pr_warn("** via the console, logs, and other interfaces. This    **\n");
> -	pr_warn("** might reduce the security of your system.            **\n");
> -	pr_warn("**                                                      **\n");
> -	pr_warn("** If you see this message and you are not debugging    **\n");
> -	pr_warn("** the kernel, report this immediately to your system   **\n");
> -	pr_warn("** administrator!                                       **\n");
> -	pr_warn("**                                                      **\n");
> -	pr_warn("**   NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE   **\n");
> -	pr_warn("**********************************************************\n");
> +	for (i = 0; i < ARRAY_SIZE(lines); i++)
> +		pr_warn("**%s**\n", no_hash_pointers_warning[lines[i]]);

+	for (i = 0; i < 3; i++)
+		pr_warn("**%s**\n", no_hash_pointers_warning[lines[2 - i]]);