From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 44E473858422 for ; Thu, 18 Nov 2021 20:06:02 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 44E473858422 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-225-ZZAxkvIlMEixUreoRDOQVg-1; Thu, 18 Nov 2021 15:05:58 -0500 X-MC-Unique: ZZAxkvIlMEixUreoRDOQVg-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 270DD802E65; Thu, 18 Nov 2021 20:05:57 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.131]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 19EDB60C05; Thu, 18 Nov 2021 20:05:55 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella Cc: libc-alpha@sourceware.org, "H . J . Lu" Subject: Re: [RFC] elf: Add elf checks for main executable References: <20211118195547.3362263-1-adhemerval.zanella@linaro.org> <871r3ddykc.fsf@oldenburg.str.redhat.com> Date: Thu, 18 Nov 2021 21:05:54 +0100 In-Reply-To: (Adhemerval Zanella's message of "Thu, 18 Nov 2021 17:02:11 -0300") Message-ID: <87o86hcjq5.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.6 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Nov 2021 20:06:03 -0000 * Adhemerval Zanella: > On 18/11/2021 17:00, Florian Weimer wrote: >> * Adhemerval Zanella: >> >>> +static inline void >>> +_dl_check_ehdr (struct link_map *main_map) >>> +{ >>> + ElfW(Ehdr) *ehdr = (void *) main_map->l_map_start; >>> + int err = _dl_elfhdr_check (ehdr); >>> + if (err != DL_ELFHDR_OK) >>> + _dl_fatal_printf ("program loading error: %s\n", _dl_elfhdr_errstr (err)); >>> +} >> >> I think you need to iterate through the load segments and see if there >> is one with p_offset == 0 and p_memsz > 0 (the ELF header is smaller >> than a page). That's the one to use for this check. If there is no >> such segment, we have to skip the check. > > Hum, should we set the l_map_start as well only if we found such segment? No, we need l_map_start in _dl_find_dso_for_object (among other places). Thanks, Florian