From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AFBB7C43218 for ; Tue, 11 Jun 2019 09:12:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C600206BA for ; Tue, 11 Jun 2019 09:12:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727726AbfFKJML (ORCPT ); Tue, 11 Jun 2019 05:12:11 -0400 Received: from elvis.franken.de ([193.175.24.41]:54846 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727642AbfFKJML (ORCPT ); Tue, 11 Jun 2019 05:12:11 -0400 X-Greylist: delayed 2723 seconds by postgrey-1.27 at vger.kernel.org; Tue, 11 Jun 2019 05:12:10 EDT Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1hac79-0005BB-00; Tue, 11 Jun 2019 10:26:43 +0200 Received: by alpha.franken.de (Postfix, from userid 1000) id 95458C0408; Tue, 11 Jun 2019 10:19:47 +0200 (CEST) Date: Tue, 11 Jun 2019 10:19:47 +0200 From: Thomas Bogendoerfer To: Hauke Mehrtens Cc: Paul Burton , "linux-mips@vger.kernel.org" , Paul Burton , Julien Cristau , Yunqiang Su , "stable@vger.kernel.org" Subject: Re: [PATCH 1/2] MIPS: Bounds check virt_addr_valid Message-ID: <20190611081947.GA11513@alpha.franken.de> References: <20190528170444.1557-1-paul.burton@mips.com> <9e5c6f1a-b4a9-dbae-6314-aeb08f31c8aa@hauke-m.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9e5c6f1a-b4a9-dbae-6314-aeb08f31c8aa@hauke-m.de> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Tue, Jun 11, 2019 at 01:41:21AM +0200, Hauke Mehrtens wrote: > On 5/28/19 7:05 PM, Paul Burton wrote: > > --- > > > > arch/mips/mm/mmap.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c > > index 2f616ebeb7e0..7755a1fad05a 100644 > > --- a/arch/mips/mm/mmap.c > > +++ b/arch/mips/mm/mmap.c > > @@ -203,6 +203,11 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) > > > > int __virt_addr_valid(const volatile void *kaddr) > > { > > + unsigned long vaddr = (unsigned long)vaddr; the second vaddr should be better kaddr > > + > > + if ((vaddr < PAGE_OFFSET) || (vaddr >= MAP_BASE)) > > + return 0; > > + > > return pfn_valid(PFN_DOWN(virt_to_phys(kaddr))); > > } > > EXPORT_SYMBOL_GPL(__virt_addr_valid); > > > > Someone complained that this compiled to a constant "return 0" for him: > https://bugs.openwrt.org/index.php?do=details&task_id=2305#comment6554 > > I just checked this on a unmodified 5.2-rc4 with the xway_defconfig and > I get this: > > 0001915c <__virt_addr_valid>: > 1915c: 03e00008 jr ra > 19160: 00001025 move v0,zero > > Is this intended? I don't think so. Interesting what the compiler decides to do here. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]