From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with archive (Exim 4.43) id 1Ll5XY-0006U8-4K for mharc-grub-devel@gnu.org; Sat, 21 Mar 2009 14:03:24 -0400 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Ll5XW-0006Tx-T9 for grub-devel@gnu.org; Sat, 21 Mar 2009 14:03:22 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Ll5XS-0006Th-Dn for grub-devel@gnu.org; Sat, 21 Mar 2009 14:03:22 -0400 Received: from [199.232.76.173] (port=49373 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Ll5XS-0006TX-91 for grub-devel@gnu.org; Sat, 21 Mar 2009 14:03:18 -0400 Received: from aybabtu.com ([69.60.117.155]:60752) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1Ll5XR-0003kE-Lv for grub-devel@gnu.org; Sat, 21 Mar 2009 14:03:17 -0400 Received: from [192.168.10.10] (helo=thorin) by aybabtu.com with esmtp (Exim 4.69) (envelope-from ) id 1Ll5OD-0005rV-Ae for grub-devel@gnu.org; Sat, 21 Mar 2009 18:53:45 +0100 Received: from rmh by thorin with local (Exim 4.69) (envelope-from ) id 1Ll5XP-0004n4-2j for grub-devel@gnu.org; Sat, 21 Mar 2009 19:03:15 +0100 Date: Sat, 21 Mar 2009 19:03:15 +0100 From: Robert Millan To: The development of GRUB 2 Message-ID: <20090321180315.GF18284@thorin> References: <49B82B65.3080506@gmail.com> <20090313191442.GC17068@thorin> <49BAC506.2030006@gmail.com> <20090313.134505.185970759.davem@davemloft.net> <49BAC797.9010200@gmail.com> <20090318101227.GB20072@thorin> <49C0F690.7060305@gmail.com> <20090321174629.GB18284@thorin> <49C52AE2.5070202@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <49C52AE2.5070202@gmail.com> Organization: free as in freedom X-Message-Flag: Worried about Outlook viruses? Switch to Thunderbird! www.mozilla.com/thunderbird X-Debbugs-No-Ack: true User-Agent: Mutt/1.5.18 (2008-05-17) X-detected-operating-system: by monty-python.gnu.org: Genre and OS details not recognized. Subject: Re: ELF bugfixes X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: The development of GRUB 2 List-Id: The development of GRUB 2 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 21 Mar 2009 18:03:23 -0000 On Sat, Mar 21, 2009 at 06:58:58PM +0100, phcoder wrote: > Robert Millan wrote: >> On Wed, Mar 18, 2009 at 02:26:40PM +0100, phcoder wrote: >>> Robert Millan wrote: >>>> On Fri, Mar 13, 2009 at 09:52:39PM +0100, phcoder wrote: >>>>> - grub_multiboot_payload_entry_offset = ehdr->e_entry - phdr(lowest_segment)->p_vaddr; >>>>> + for (i = 0; i < ehdr->e_phnum; i++) >>>>> + if (phdr(i)->p_vaddr <= ehdr->e_entry + && phdr(i)->p_vaddr >>>>> + phdr(i)->p_memsz > ehdr->e_entry) >>>>> + grub_multiboot_payload_entry_offset = (ehdr->e_entry - phdr(i)->p_vaddr) >>>>> + + (phdr(i)->p_paddr - phdr(lowest_segment)->p_paddr); >>>> You need to handle the case in which grub_multiboot_payload_entry_offset is left >>>> uninitialized (it needs to be initialized each time the multiboot command is >>>> run, not just when the module is loaded). >>>> >>> module? actually it's when loading image. Perhaps you mean that >>> additional error check is necessary >> >> I meant GRUB's multiboot.mod, not the payload's module. Sorry I wasn't clear. >> > With this error check if grub_multiboot_payload_entry_offset it can > happen only if no image is loaded. And actually > grub_multiboot_payload_entry_offset is set to 0 at multiboot.mod load > So I don't really understand the problem You can't rely on grub_multiboot_payload_entry_offset being set to 0, because any subsequent call of "multiboot /something" has the potential to override this. You must not assume the multiboot command is only going to be run once. -- Robert Millan The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and how) you may access your data; but nobody's threatening your freedom: we still allow you to remove your data and not access it at all."