From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 872EA6B0292 for ; Mon, 17 Jul 2017 13:55:04 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id e199so171160178pfh.7 for ; Mon, 17 Jul 2017 10:55:04 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [65.50.211.133]) by mx.google.com with ESMTPS id b5si12946965pfe.489.2017.07.17.10.55.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 17 Jul 2017 10:55:03 -0700 (PDT) Date: Mon, 17 Jul 2017 10:54:59 -0700 From: Matthew Wilcox Subject: Re: [PATCH 1/1] mm/slub.c: add a naive detection of double free or corruption Message-ID: <20170717175459.GC14983@bombadil.infradead.org> References: <1500309907-9357-1-git-send-email-alex.popov@linux.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1500309907-9357-1-git-send-email-alex.popov@linux.com> Sender: owner-linux-mm@kvack.org List-ID: To: Alexander Popov Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, keescook@chromium.org On Mon, Jul 17, 2017 at 07:45:07PM +0300, Alexander Popov wrote: > Add an assertion similar to "fasttop" check in GNU C Library allocator: > an object added to a singly linked freelist should not point to itself. > That helps to detect some double free errors (e.g. CVE-2017-2636) without > slub_debug and KASAN. Testing with hackbench doesn't show any noticeable > performance penalty. > { > + BUG_ON(object == fp); /* naive detection of double free or corruption */ > *(void **)(object + s->offset) = fp; > } Is BUG() the best response to this situation? If it's a corruption, then yes, but if we spot a double-free, then surely we should WARN() and return without doing anything? -- 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