Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757726AbZGJXNZ (ORCPT ); Fri, 10 Jul 2009 19:13:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756741AbZGJXNQ (ORCPT ); Fri, 10 Jul 2009 19:13:16 -0400 Received: from e3.ny.us.ibm.com ([32.97.182.143]:42362 "EHLO e3.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754967AbZGJXNP (ORCPT ); Fri, 10 Jul 2009 19:13:15 -0400 Date: Fri, 10 Jul 2009 18:13:13 -0500 From: Sonny Rao To: tglx@linuxtronix.de Cc: mingo@redhat.com, linux-kernel@vger.kernel.org, linux-mm@vger.kernel.org, sonnyrao@us.ibm.com, stable@kernel.org, anton@samba.org, rajamony@us.ibm.com, speight@us.ibm.com, mstephen@us.ibm.com, grimm@us.ibm.com, mikey@ozlabs.au.ibm.com Subject: [PATCH] futexs: fix infinite loop in get_futex_key on huge page Message-ID: <20090710231313.GA23572@us.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1128 Lines: 29 get_futex_key() can infinitely loop if it is called on a virtual address that is within a huge page but not aligned to the beginning of that page. The call to get_user_pages_fast will return the struct page for a sub-page within the huge page and the check for page->mapping will always fail. The fix is to call compound_head on the page before checking that it's mapped. Signed-off-by: Sonny Rao Cc: Ingo Molnar Cc: stable@kernel.org Index: linux-2.6.31-rc2/kernel/futex.c =================================================================== --- linux-2.6.31-rc2.orig/kernel/futex.c 2009-07-10 17:45:46.181084475 -0500 +++ linux-2.6.31-rc2/kernel/futex.c 2009-07-10 17:46:47.345084062 -0500 @@ -247,6 +247,7 @@ if (err < 0) return err; + page = compound_head(page); lock_page(page); if (!page->mapping) { unlock_page(page); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/