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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 27B6DCA9EC0 for ; Mon, 28 Oct 2019 22:49:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E4E90214E0 for ; Mon, 28 Oct 2019 22:49:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="i/IpsRc5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730022AbfJ1WtT (ORCPT ); Mon, 28 Oct 2019 18:49:19 -0400 Received: from mail-wr1-f49.google.com ([209.85.221.49]:38416 "EHLO mail-wr1-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725867AbfJ1WtT (ORCPT ); Mon, 28 Oct 2019 18:49:19 -0400 Received: by mail-wr1-f49.google.com with SMTP id v9so11592944wrq.5; Mon, 28 Oct 2019 15:49:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=A2jEsBOs5Fgq1k1SUjS53cvLXGYRrdoo13cMo5AIHyk=; b=i/IpsRc5S8qtvd4Hd2Jajl2muQJLkQ9Z8YMjvk6JZSa68F2SqLABksVza3TMROQk1l /4QBiNY1iKt19N2BdTTsYSNeafJcDTRO2E4QtC+5aruM0hW4mtc5ftJT2S5L8GFlPVO6 YKMW91bU1FKH8m7wjlo0qMRlZEa5yscXWnOT5TtkxhV6uvyZw6int+SGf31E8CCgtgK/ +PnCW1FPhrNJnrlSQzaig+42FGFhZKigWWA1U5aJGoTzmzNKFNpQRyc3dJn4Eh6uVJle kVA2eUWPyplVvIfzyavyLQm4lpmFVVkZvdSAmIfbVaktYI6/5+jFr0jbVFruWSb1RxEh +Lzw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=A2jEsBOs5Fgq1k1SUjS53cvLXGYRrdoo13cMo5AIHyk=; b=DOrr8kb/MjohnRRbaqHcEszxolytGIe8Dgei8oQL1LUrA3Nff//Mxuf5qNwQxA0nBS xWxojUwDCOKhrHjhWThGDZTEr/kfdW8XkZGc/5YTIk5nWlSq0gyMC6zurDNAwoabSCXC U3l27oaFPvOs65VVKUg8CcEx7mvB9JTDFQ4NQTSFEhbfFJyXYrBHPyj/xaA21wELXaz+ QMIa1AsxYTtH20yqWcBcPQ+12sCEP8ZnKHJZKXEl+ISnczRuO9PPgwD1K1rpFQ/9UAJk 0+rqcdSAS847FnL6IxOra+VK9IsNCRrf1HaOWO7BWSLspaj4yPeekfr6KS0J8kUw/o/x ZxTA== X-Gm-Message-State: APjAAAUld68BVZGsIO9kwDqZGaTytTsHKb6Y7shLIUpugWCzg05ViHpe x3Ky8nPzqOFpaLpa5JTXKaIA5eXI X-Google-Smtp-Source: APXvYqxkisLhWG9uNXHLiB27lzGZOriN/QcZjrQazkEnS+bedp3Okzy6CzZwUI/6m/n3bBjwuOviOg== X-Received: by 2002:adf:f44e:: with SMTP id f14mr16228477wrp.56.1572302957156; Mon, 28 Oct 2019 15:49:17 -0700 (PDT) Received: from desk.local ([2a02:a03f:40ac:ce00:6dcd:e18f:2cd1:7611]) by smtp.gmail.com with ESMTPSA id u7sm14094078wre.59.2019.10.28.15.49.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Oct 2019 15:49:16 -0700 (PDT) Date: Mon, 28 Oct 2019 23:49:15 +0100 From: Luc Van Oostenryck To: Rasmus Villemoes Cc: Dan Carpenter , linux-sparse@vger.kernel.org, LKML Subject: Re: detecting misuse of of_get_property Message-ID: <20191028224914.enpqjkcvbxyeexnl@desk.local> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 28, 2019 at 08:32:42PM +0100, Rasmus Villemoes wrote: > Hi, > > I just spent some time trying to convert some so far PPC-only drivers to > be more generic. One of the things I had to do was convert stuff like > > u32 *val = of_get_property(np, "bla", NULL); > do_stuff_with(*val); > > with > > of_property_read_u32(np, "bla", &val); > do_stuff_with(val); > > (error checking omitted for simplicity). The problem is that > of_get_property() just returns void*. When the property is just a > string, there's no problem interpreting that as a char*. But when the > property is a number of array of numbers, I'd like some way to flag > casting it to u32* as an error - if you cast it to a (pointer to integer > type wider than char), it must be to a __be32*. Is there some way > sparse/smatch could help find such cases? If I understand you correctly, you would need a kind of 'soft' bitwise pointer? I guess it shouldn't be too hard to add a new flag which would allow cast of bitwise pointers to pointers to char/void (see at end of evaluate.c:evaluate_cast()). Note: casts from bitwise pointer to void* are already allowed. -- Luc