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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 08033C43219 for ; Sat, 4 May 2019 16:33:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D7C7C2053B for ; Sat, 4 May 2019 16:33:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727020AbfEDQdD (ORCPT ); Sat, 4 May 2019 12:33:03 -0400 Received: from 0.ictbs.com ([203.137.112.168]:43172 "EHLO 0.ictbs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726244AbfEDQdD (ORCPT ); Sat, 4 May 2019 12:33:03 -0400 X-Greylist: delayed 382 seconds by postgrey-1.27 at vger.kernel.org; Sat, 04 May 2019 12:33:02 EDT Received: by hq.local (Postfix, from userid 1000) id 0754F66477; Sat, 4 May 2019 18:26:33 +0200 (CEST) Date: Sat, 4 May 2019 18:26:33 +0200 From: Victor Bravo <1905@spmblk.com> To: Arend van Spriel , Franky Lin , Hante Meuleman , Chi-Hsien Lin , Wright Feng , Kalle Valo , "David S. Miller" , linux-wireless@vger.kernel.org, brcm80211-dev-list.pdl@broadcom.com, brcm80211-dev-list@cypress.com, linux-kernel@vger.kernel.org Subject: PROBLEM: brcmfmac's DMI-based fw file names break built-in fw loader Message-ID: <20190504162633.ldrz2nqfocg55grb@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The brcmfmac driver seems to have partially fixed problems which prevented it to be used in shared system/kernel images for multiple hardware by trying to load it's .txt as ...txt first and then falling back to .txt. Real-life example: brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43340-sdio.ASUSTeK COMPUTER INC.-T100HAN.txt failed with error -2 brcmfmac: brcmf_fw_alloc_request: using brcm/brcmfmac43340-sdio for chip BCM43340/2 Unfortunately this doesn't really help on systems which use static kernel with firmware blobs (and also text configuration files in case of brcmfmac) built-in using CONFIG_EXTRA_FIRMWARE, as CONFIG_EXTRA_FIRMWARE doesn't support spaces in file names - kernel build fails with CONFIG_EXTRA_FIRMWARE="brcm/brcmfmac43340-sdio.bin brcm/brcmfmac43340-sdio.ASUSTeK COMPUTER INC.-T100HAN.txt" for obvious reasons. So the only way here is to stay with good old brcmfmac43340-sdio.txt and support at most one brcmfmac-equipped machine per kernel image. Please consider filtering the DMI strings and replacing spaces and possibly other invalid characters with underscores, and/or adding module parameter to allow passing the string from command line (using brcmfmac.tag=t100 or brcmfmac.board=t100 to make the module load brcmfmac43340-sdio.t100.txt seems nicer to me, and isn't prone to breaking when DMI strings change on BIOS update). My brief grep-based research also suggest that strings retrieved by dmi_get_system_info() are passed to firmware loader without any checks for special character, /../ etc. I'm not sure whether this is considered to be proper & safe use, but if it's not, it may also have some security implications, as it allows attacker with access to DMI strings (using root rights/other OS/BIOS/physical access) to mess with kernel space or secure boot. I would also really appreciate not allowing future brcm (and other) drivers to leave staging area before they fully support =y. Regards, v.b.