From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id C22BC6B0201 for ; Wed, 24 Mar 2010 17:20:15 -0400 (EDT) Date: Wed, 24 Mar 2010 16:19:24 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH 07/11] Memory compaction core In-Reply-To: <20100324141400.72479ce6.akpm@linux-foundation.org> Message-ID: References: <1269347146-7461-1-git-send-email-mel@csn.ul.ie> <1269347146-7461-8-git-send-email-mel@csn.ul.ie> <20100324133347.9b4b2789.akpm@linux-foundation.org> <20100324145946.372f3f31@bike.lwn.net> <20100324141400.72479ce6.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Jonathan Corbet , Mel Gorman , Andrea Arcangeli , Adam Litke , Avi Kivity , David Rientjes , Minchan Kim , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Wed, 24 Mar 2010, Andrew Morton wrote: > > ...except that we've seen a fair number of null pointer dereference > > exploits that have told us something altogether different. Are we > > *sure* we don't want to test for null pointers...? > > > > It's hard to see what the test gains us really - the kernel has > zillions of pointer derefs, any of which could be NULL if we have a > bug. Are we more likely to have a bug here than elsewhere? > > This one will oops on a plain old read, so it's a bit moot in this > case. If the object pointed to is larger than page size and we are referencing a member with an offset larger than page size later then we may create an exploit without checks. But the structure here is certainly smaller than that. So no issue here. -- 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