Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753407Ab3CKRhM (ORCPT ); Mon, 11 Mar 2013 13:37:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44494 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751247Ab3CKRhK (ORCPT ); Mon, 11 Mar 2013 13:37:10 -0400 Date: Mon, 11 Mar 2013 13:36:50 -0400 From: Vivek Goyal To: HATAYAMA Daisuke Cc: zhangyanfei@cn.fujitsu.com, kexec@lists.infradead.org, heiko.carstens@de.ibm.com, linux-kernel@vger.kernel.org, lisa.mitchell@hp.com, kumagai-atsushi@mxc.nes.nec.co.jp, ebiederm@xmission.com, akpm@linux-foundation.org, cpw@sgi.com Subject: Re: [PATCH v2 01/20] vmcore: refer to e_phoff member explicitly Message-ID: <20130311173650.GG8482@redhat.com> References: <20130302083554.31252.30615.stgit@localhost6.localdomain6> <5135A054.7010401@cn.fujitsu.com> <513C2C47.5020008@cn.fujitsu.com> <20130311.093141.331282420.d.hatayama@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20130311.093141.331282420.d.hatayama@jp.fujitsu.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1875 Lines: 45 On Mon, Mar 11, 2013 at 09:31:41AM +0900, HATAYAMA Daisuke wrote: > From: Zhang Yanfei > Subject: Re: [PATCH v2 01/20] vmcore: refer to e_phoff member explicitly > Date: Sun, 10 Mar 2013 14:46:31 +0800 > > > 于 2013年03月05日 15:35, Zhang Yanfei 写道: > >> 于 2013年03月02日 16:35, HATAYAMA Daisuke 写道: > > > > > One minor suggestion. > > > > Previously, when the code assumes program headers are following immediately > > the ELF header, it uses > > > > elfcorebuf_sz = sizeof(Elf64_Ehdr) + ehdr.e_phnum * sizeof(Elf64_Phdr); > > > > to calculate the size of ELF header and ELF program headers > > > > This patch avoids the assumption, and uses ehdr.e_phoff to get the program > > headers' address. But it will read unrelated contents into elfcorebuf if > > program headers are not following immediately the ELF header. So could the > > code be: > > > > elfcorebuf_sz = sizeof(Elf64_Ehdr) + ehdr.e_phnum * sizeof(Elf64_Phdr); > > addr = elfcorehdr_addr + ehdr.e_phoff; > > memcpy(elfcorebuf, &ehdr, sizeof(Elf64_Ehdr)); > > read_from_oldmem(elfcorebuf + sizeof(Elf64_Ehdr), elfcorebuf_sz - > > sizeof(Elf64_Ehdr), &addr, 0); > > (Elf64_Ehdr *)elfcorebuf->e_phoff = sizeof(Elf64_Ehdr); > > Thanks. This is not minor suggestion. This is critical. My code is > completely broken. On ELF, segments and headers other than ELF header > can occur in any positions. This means program header table can occur > after segments. So, on terabyte systems, e_phoff can be more than > terabytes. Agreed. It is safer to not copy al the bits till e_phoff. Thanks Vivek -- 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/