From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754009AbdJIK6S (ORCPT ); Mon, 9 Oct 2017 06:58:18 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:34857 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751598AbdJIK6Q (ORCPT ); Mon, 9 Oct 2017 06:58:16 -0400 X-Google-Smtp-Source: AOwi7QDjWh1+E4+caEWR/D5sXCmWaPAYgN0wEEDmElzS8eJDsUYpHMY5t/nVggAWRD18kry+ShY78w== Subject: Re: [PATCH] KVM: remove printing of token address To: "Tobin C. Harding" Cc: rkrcmar@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <1507530614-10504-1-git-send-email-me@tobin.cc> <1845029054.11118038.1507535378802.JavaMail.zimbra@redhat.com> <20171009100415.GA12785@eros> From: Paolo Bonzini Message-ID: Date: Mon, 9 Oct 2017 12:58:12 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20171009100415.GA12785@eros> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/10/2017 12:04, Tobin C. Harding wrote: > On Mon, Oct 09, 2017 at 03:49:38AM -0400, Paolo Bonzini wrote: >> >> >> ----- Original Message ----- >>> From: "Tobin C. Harding" >>> To: "Paolo Bonzini" , rkrcmar@redhat.com >>> Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, "Tobin C. Harding" >>> Sent: Monday, October 9, 2017 8:30:14 AM >>> Subject: [PATCH] KVM: remove printing of token address >>> >>> KVM currently prints the address of the consumer token. It is not >>> immediately clear what benefit it is to see this address. Printing >>> this address leaks kernel pointers into dmesg and is a security risk. >>> >>> Remove the consumer token address from error message output. >> >> It should use %pK instead. > > Is there any other way we can identify a token? There is some push back against kpt_restrict (as > used by %pK) at the moment. If there is another sane way to do it perhaps we could consider that, > else I'll use %pK for v2. Not really, we know it is an eventfd but you can't go from the struct eventfd_ctx* (the token) to the corresponding struct file. I'm not sure about the pushback... I've read your name in https://lwn.net/Articles/735589/ :) and that article says "the same effect as a restrictive kptr_restrict setting could be achieved by searching for (and fixing) every use of unadorned "%p" directives in the kernel". As I understand it, the push back is against restrictive kptr_restrict settings, not against using "%pK" _to avoid the need_ for such a restrictive setting. Thanks, Paolo >> Also, please do the same change on the VFIO >> side (drivers/vfio/pci/vfio_pci_intrs.c, call to irq_bypass_register_producer). > > Oh, cool. I was wondering where the other side was. Will send v2 > > thanks, > Tobin. >