From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755056AbcGHMKH (ORCPT ); Fri, 8 Jul 2016 08:10:07 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52526 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754731AbcGHMKE (ORCPT ); Fri, 8 Jul 2016 08:10:04 -0400 Date: Fri, 8 Jul 2016 05:08:55 -0700 From: tip-bot for Jiri Kosina Message-ID: Cc: jkosina@suse.cz, linux-kernel@vger.kernel.org, brgerst@gmail.com, torvalds@linux-foundation.org, toshi.kani@hp.com, mcgrof@suse.com, dvlasenk@redhat.com, hpa@zytor.com, mingo@kernel.org, jpoimboe@redhat.com, akpm@linux-foundation.org, keescook@chromium.org, peterz@infradead.org, tglx@linutronix.de, bp@alien8.de, luto@kernel.org Reply-To: torvalds@linux-foundation.org, toshi.kani@hp.com, mcgrof@suse.com, dvlasenk@redhat.com, hpa@zytor.com, jkosina@suse.cz, linux-kernel@vger.kernel.org, brgerst@gmail.com, luto@kernel.org, bp@alien8.de, jpoimboe@redhat.com, akpm@linux-foundation.org, mingo@kernel.org, peterz@infradead.org, tglx@linutronix.de, keescook@chromium.org In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/mm] x86/mm/pat, /dev/mem: Remove superfluous error message Git-Commit-ID: 39380b80d72723282f0ea1d1bbf2294eae45013e X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 39380b80d72723282f0ea1d1bbf2294eae45013e Gitweb: http://git.kernel.org/tip/39380b80d72723282f0ea1d1bbf2294eae45013e Author: Jiri Kosina AuthorDate: Fri, 8 Jul 2016 11:38:28 +0200 Committer: Ingo Molnar CommitDate: Fri, 8 Jul 2016 11:52:58 +0200 x86/mm/pat, /dev/mem: Remove superfluous error message Currently it's possible for broken (or malicious) userspace to flood a kernel log indefinitely with messages a-la Program dmidecode tried to access /dev/mem between f0000->100000 because range_is_allowed() is case of CONFIG_STRICT_DEVMEM being turned on dumps this information each and every time devmem_is_allowed() fails. Reportedly userspace that is able to trigger contignuous flow of these messages exists. It would be possible to rate limit this message, but that'd have a questionable value; the administrator wouldn't get information about all the failing accessess, so then the information would be both superfluous and incomplete at the same time :) Returning EPERM (which is what is actually happening) is enough indication for userspace what has happened; no need to log this particular error as some sort of special condition. Signed-off-by: Jiri Kosina Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Kees Cook Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Toshi Kani Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1607081137020.24757@cbobk.fhfr.pm Signed-off-by: Ingo Molnar --- arch/x86/mm/pat.c | 5 +---- drivers/char/mem.c | 6 +----- 2 files changed, 2 insertions(+), 9 deletions(-) diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c index fb0604f..db00e3e 100644 --- a/arch/x86/mm/pat.c +++ b/arch/x86/mm/pat.c @@ -755,11 +755,8 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size) return 1; while (cursor < to) { - if (!devmem_is_allowed(pfn)) { - pr_info("x86/PAT: Program %s tried to access /dev/mem between [mem %#010Lx-%#010Lx], PAT prevents it\n", - current->comm, from, to - 1); + if (!devmem_is_allowed(pfn)) return 0; - } cursor += PAGE_SIZE; pfn++; } diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 71025c2..d633974 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -66,12 +66,8 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size) u64 cursor = from; while (cursor < to) { - if (!devmem_is_allowed(pfn)) { - printk(KERN_INFO - "Program %s tried to access /dev/mem between %Lx->%Lx.\n", - current->comm, from, to); + if (!devmem_is_allowed(pfn)) return 0; - } cursor += PAGE_SIZE; pfn++; }