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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 038D7C433E0 for ; Wed, 3 Feb 2021 09:54:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 43D6964F60 for ; Wed, 3 Feb 2021 09:54:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 43D6964F60 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A67216B0006; Wed, 3 Feb 2021 04:54:26 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id A3F0A6B006C; Wed, 3 Feb 2021 04:54:26 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 955F16B006E; Wed, 3 Feb 2021 04:54:26 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0073.hostedemail.com [216.40.44.73]) by kanga.kvack.org (Postfix) with ESMTP id 7AE996B0006 for ; Wed, 3 Feb 2021 04:54:26 -0500 (EST) Received: from smtpin19.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 4656610FEF for ; Wed, 3 Feb 2021 09:54:26 +0000 (UTC) X-FDA: 77776496532.19.story99_031462b275d2 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin19.hostedemail.com (Postfix) with ESMTP id 1C38D1AD1B3 for ; Wed, 3 Feb 2021 09:54:26 +0000 (UTC) X-HE-Tag: story99_031462b275d2 X-Filterd-Recvd-Size: 3941 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Wed, 3 Feb 2021 09:54:25 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1612346064; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=W5joaEFyKEmxsNgxXWQzVbFGdC1MUWlZwutGUmy8/jo=; b=Czj/9S9jYfh4hGtMrHwynewDHibaO+tpS/h6ERXNMaoz1jYV/uhHFpHE2yDZz6KyMATppF NkhjXUqOa0e6u386/k5tHN7+AMLcNBxeH5vlpkQgWDz64rfh2bsevcp4CwgxzQVR5Xib8y Be/JT6VIXttyduSzKWy+gH/Dntbt7lY= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 203F8AF4C; Wed, 3 Feb 2021 09:54:24 +0000 (UTC) Date: Wed, 3 Feb 2021 10:54:23 +0100 From: Petr Mladek To: Timur Tabi Cc: Steven Rostedt , Sergey Senozhatsky , linux-kernel@vger.kernel.org, vbabka@suse.cz, linux-mm@kvack.org, willy@infradead.org, akpm@linux-foundation.org, torvalds@linux-foundation.org, roman.fietze@magna.com, keescook@chromium.org, john.ogness@linutronix.de, akinobu.mita@gmail.com Subject: Re: [PATCH][RESEND] lib/vsprintf: make-printk-non-secret printks all addresses as unhashed Message-ID: References: <20210202213633.755469-1-timur@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210202213633.755469-1-timur@kernel.org> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue 2021-02-02 15:36:33, Timur Tabi wrote: > If the make-printk-non-secret command-line parameter is set, then > printk("%p") will print addresses as unhashed. This is useful for > debugging purposes. > > A large warning message is displayed if this option is enabled, > because unhashed addresses, while useful for debugging, exposes > kernel addresses which can be a security risk. > > Signed-off-by: Timur Tabi > --- > lib/vsprintf.c | 34 ++++++++++++++++++++++++++++++++-- > 1 file changed, 32 insertions(+), 2 deletions(-) Please, add also entry into Documentation/admin-guide/kernel-parameters.txt. If we agree that the parameter is acceptable then let's make it properly. > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index 3b53c73580c5..b9f87084afb0 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -2090,6 +2090,30 @@ char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode, > return widen_string(buf, buf - buf_start, end, spec); > } > > +/* Disable pointer hashing if requested */ > +static bool debug_never_hash_pointers __ro_after_init; > + > +static int __init debug_never_hash_pointers_enable(char *str) > +{ > + debug_never_hash_pointers = true; > + pr_warn("**********************************************************\n"); > + pr_warn("** NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE NOTICE **\n"); > + pr_warn("** **\n"); > + pr_warn("** All pointers that are printed to the console will **\n"); > + pr_warn("** be printed as unhashed. **\n"); > + pr_warn("** **\n"); > + pr_warn("** Kernel memory addresses are exposed, which may **\n"); > + pr_warn("** compromise security on 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 vendor! **\n"); It is a boot parameter. So it should be "system administrtor" instead of vendor. Otherwise, it looks good to me. Best Regards, Petr