From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f44.google.com (mail-wg0-f44.google.com [74.125.82.44]) by kanga.kvack.org (Postfix) with ESMTP id 334896B0032 for ; Fri, 24 Apr 2015 17:06:17 -0400 (EDT) Received: by wgso17 with SMTP id o17so62805438wgs.1 for ; Fri, 24 Apr 2015 14:06:16 -0700 (PDT) Received: from mail-wi0-f177.google.com (mail-wi0-f177.google.com. [209.85.212.177]) by mx.google.com with ESMTPS id yx7si21196031wjc.202.2015.04.24.14.06.15 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 24 Apr 2015 14:06:15 -0700 (PDT) Received: by widdi4 with SMTP id di4so35814645wid.0 for ; Fri, 24 Apr 2015 14:06:15 -0700 (PDT) From: Anisse Astier Subject: [PATCH 0/2] Sanitizing freed pages Date: Fri, 24 Apr 2015 23:05:47 +0200 Message-Id: <1429909549-11726-1-git-send-email-anisse@astier.eu> Sender: owner-linux-mm@kvack.org List-ID: Cc: Anisse Astier , Andrew Morton , Mel Gorman , "Kirill A. Shutemov" , David Rientjes , Alan Cox , Linus Torvalds , Peter Zijlstra , PaX Team , Brad Spengler , Kees Cook , linux-mm@kvack.org, linux-kernel@vger.kernel.org Hi, I'm trying revive an old debate here[1], though with a simpler approach than was previously tried. This patch series implements a new option to sanitize freed pages, a (very) small subset of what is done in PaX/grsecurity[3], inspired by a previous submission [4]. The first patch is fairly independent, and could be taken as-is. The second is the meat and should be straight-forward to review. There are a few different uses that this can cover: - some cases of use-after-free could be detected (crashes), although this not as efficient as KAsan/kmemcheck - it can help with long-term memory consumption in an environment with multiple VMs and Kernel Same-page Merging on the host. [2] - finally, it can reduce infoleaks, although this is hard to measure. The approach is voluntarily kept as simple as possible. A single configuration option, no command line option, no sysctl nob. It can of course be changed, although I'd be wary of runtime-configuration options that could be used for races. I haven't been able to measure a meaningful performance difference when compiling a (in-cache) kernel; I'd be interested to see what difference it makes with your particular workload/hardware (I suspect mine is CPU-bound on this small laptop). [1] https://lwn.net/Articles/334747/ [2] https://staff.aist.go.jp/k.suzaki/EuroSec12-SUZAKI-revised2.pdf [3] http://en.wikibooks.org/wiki/Grsecurity/Appendix/Grsecurity_and_PaX_Configuration_Options#Sanitize_all_freed_memory [4] http://article.gmane.org/gmane.linux.kernel.mm/34398 Anisse Astier (2): mm/page_alloc.c: cleanup obsolete KM_USER* mm/page_alloc.c: add config option to sanitize freed pages mm/Kconfig | 12 ++++++++++++ mm/page_alloc.c | 15 +++++++-------- 2 files changed, 19 insertions(+), 8 deletions(-) -- 1.9.3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org