From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx201.postini.com [74.125.245.201]) by kanga.kvack.org (Postfix) with SMTP id B55EF6B005A for ; Wed, 11 Jan 2012 17:34:41 -0500 (EST) Date: Wed, 11 Jan 2012 14:34:39 -0800 From: Andrew Morton Subject: Re: [PATCH] mm: Fix NULL ptr dereference in __count_immobile_pages Message-Id: <20120111143439.538bf274.akpm@linux-foundation.org> In-Reply-To: <1326213022-11761-1-git-send-email-mhocko@suse.cz> References: <1326213022-11761-1-git-send-email-mhocko@suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman , KAMEZAWA Hiroyuki , Andrea Arcangeli , David Rientjes On Tue, 10 Jan 2012 17:30:22 +0100 Michal Hocko wrote: > This patch fixes the following NULL ptr dereference caused by > cat /sys/devices/system/memory/memory0/removable: Which is world-readable, I assume? > ... > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5608,6 +5608,17 @@ __count_immobile_pages(struct zone *zone, struct page *page, int count) > bool is_pageblock_removable_nolock(struct page *page) > { > struct zone *zone = page_zone(page); > + unsigned long pfn = page_to_pfn(page); > + > + /* > + * We have to be careful here because we are iterating over memory > + * sections which are not zone aware so we might end up outside of > + * the zone but still within the section. > + */ > + if (!zone || zone->zone_start_pfn > pfn || > + zone->zone_start_pfn + zone->spanned_pages <= pfn) > + return false; > + > return __count_immobile_pages(zone, page, 0); > } So I propose that we backport it into -stable? -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org