From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752845AbZJYQVK (ORCPT ); Sun, 25 Oct 2009 12:21:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752330AbZJYQVJ (ORCPT ); Sun, 25 Oct 2009 12:21:09 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:48459 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752182AbZJYQVI (ORCPT ); Sun, 25 Oct 2009 12:21:08 -0400 Date: Sun, 25 Oct 2009 17:20:18 +0100 From: Ingo Molnar To: Jiri Slaby Cc: mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org, Vivek Goyal , "Eric W. Biederman" , Simon Horman , Paul Mundt Subject: Re: [PATCH 1/1] crash_dump: fix non-pae kdump kernel memory accesses Message-ID: <20091025162018.GB20391@elte.hu> References: <1256312729-22935-1-git-send-email-jirislaby@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1256312729-22935-1-git-send-email-jirislaby@gmail.com> User-Agent: Mutt/1.5.19 (2009-01-05) X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=none autolearn=no SpamAssassin version=3.2.5 _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jiri Slaby wrote: > Non-PAE 32-bit dump kernels may wrap an address around 4G and > poke unwanted space. ptes there are 32-bit long, and since > pfn << PAGE_SIZE may exceed this limit, high pfn bits are cropped > and wrong address mapped by kmap_atomic_pfn in copy_oldmem_page. > > Don't allow this behavior in non-PAE kdump kernels by checking > pfns passed into copy_oldmem_page. In the case of failure, > userspace process gets EFAULT. > > Signed-off-by: Jiri Slaby > Cc: Vivek Goyal > Cc: "Eric W. Biederman" > Cc: Simon Horman > Cc: Paul Mundt > Cc: Ingo Molnar > --- > arch/x86/kernel/crash_dump_32.c | 16 ++++++++++++++++ > 1 files changed, 16 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kernel/crash_dump_32.c b/arch/x86/kernel/crash_dump_32.c > index f7cdb3b..b78dab8 100644 > --- a/arch/x86/kernel/crash_dump_32.c > +++ b/arch/x86/kernel/crash_dump_32.c > @@ -16,6 +16,19 @@ static void *kdump_buf_page; > /* Stores the physical address of elf header of crash image. */ > unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; > > +#ifndef CONFIG_X86_PAE > +/* non-PAE kdump kernel executed from a PAE one will crop high pte bits and > + poke unwanted space counting again from address 0, we don't want that */ > +static inline bool is_crashed_pfn_valid(unsigned long pfn) > +{ > + /* on non-PAE pte must fit into unsigned long > + in fact the test is (pfn & 0x000fffff) */ > + return pte_pfn(pfn_pte(pfn, __pgprot(0))) == pfn; > +} > +#else > +static inline bool is_crashed_pfn_valid(unsigned long pfn) { return true; } > +#endif i'd suggest to push the #ifdef inside the function. Also, please use the customary (multi-line) comment style: /* * Comment ..... * ...... goes here. */ specified in Documentation/CodingStyle. Thanks, Ingo