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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF92FC433F5 for ; Wed, 11 May 2022 23:25:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 284B76B0074; Wed, 11 May 2022 19:25:14 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 233826B0075; Wed, 11 May 2022 19:25:14 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0AEC76B0078; Wed, 11 May 2022 19:25:14 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id E9EA06B0074 for ; Wed, 11 May 2022 19:25:13 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay11.hostedemail.com (Postfix) with ESMTP id C37FE81D87 for ; Wed, 11 May 2022 23:25:13 +0000 (UTC) X-FDA: 79455045306.16.F429EB5 Received: from mail-pg1-f181.google.com (mail-pg1-f181.google.com [209.85.215.181]) by imf20.hostedemail.com (Postfix) with ESMTP id CFDA11C00AE for ; Wed, 11 May 2022 23:25:03 +0000 (UTC) Received: by mail-pg1-f181.google.com with SMTP id 7so3049733pga.12 for ; Wed, 11 May 2022 16:25:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=/ki49xHqa46J2jAs7ta/eJtZ8QS3SBu8XEWl7+OO2No=; b=FhScX8YR/t+vuAsu1redHAA4dDPOcMsoT3Bq+dzybnZ3agrhS1LJ82u+gJrbLnbC8A hrKKxi5iv3ybGmAYitDOps4nXz87M944fN4oMkhk1uFkNFlc6EYWAzxfJfrLwTCTuLes 4rZNEMAUENDzVKr1twRJ/olrDDqwPfrLj0+3k= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=/ki49xHqa46J2jAs7ta/eJtZ8QS3SBu8XEWl7+OO2No=; b=d1Qf6F36EqBUuLDbNE9iVbvtGjkhDFZMkpaCYU1Ir2138//vjcshC5cf/3W41UkTUd cS+otcdW32YbYCG2+6PSnAhGe833e84zAcJ5cj8OxWT8x1cHLdY7gE8yMBvgKesfLNu2 +pPUD2ukLA7gJnG+Jrxw+C1oTPFRPpNceHY9QWd9BYdxMBCppyECHUU4MYRcBnouGder 2LLYdNdHBqmvNzIvTPzHnKKITpj3JuMPq5ey6ppbFPPaR+9jd7FQpZmhmot7tVtzv3Ru iMHFZKjYkeYlEGykKT7WlKbS66jmrTl4ACBgVlUqsh7NO+/gMr+bXmW/rqXKMoK9XvJv YxFA== X-Gm-Message-State: AOAM532GI8m/X7XF+bfUOBLUf6uCQdiFWPoAOmvFZTf3eOJrLaQB9CUe lm6v+zx0GVrxYFagKcwUr14mUA== X-Google-Smtp-Source: ABdhPJzMcvdao9wgCqtHsLuaqbFD5VrRt/A5zEaBjVmcMJGr1jzZWaoQvr9OGs1D6j+yLudNM/YImA== X-Received: by 2002:a63:d408:0:b0:3c6:e382:c157 with SMTP id a8-20020a63d408000000b003c6e382c157mr10022534pgh.470.1652311512304; Wed, 11 May 2022 16:25:12 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id e11-20020a63370b000000b003c14af5061esm407098pga.54.2022.05.11.16.25.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 May 2022 16:25:11 -0700 (PDT) Date: Wed, 11 May 2022 16:25:11 -0700 From: Kees Cook To: Jakub Kicinski Cc: "Matthew Wilcox (Oracle)" , Christoph Hellwig , "David S. Miller" , Paolo Abeni , Du Cheng , Christophe JAILLET , Vlastimil Babka , William Kucharski , Arnd Bergmann , Nathan Chancellor , netdev@vger.kernel.org, linux-mm@kvack.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] niu: Silence randstruct warnings Message-ID: <202205111624.60295F3A2@keescook> References: <20220510205729.3574400-1-keescook@chromium.org> <20220511151647.7290adbe@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220511151647.7290adbe@kernel.org> X-Rspamd-Queue-Id: CFDA11C00AE X-Stat-Signature: 7mupqd4ujnipx7o6dc6xk966ajgid1i4 Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=FhScX8YR; dmarc=pass (policy=none) header.from=chromium.org; spf=pass (imf20.hostedemail.com: domain of keescook@chromium.org designates 209.85.215.181 as permitted sender) smtp.mailfrom=keescook@chromium.org X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1652311503-699704 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, May 11, 2022 at 03:16:47PM -0700, Jakub Kicinski wrote: > On Tue, 10 May 2022 13:57:29 -0700 Kees Cook wrote: > > Clang randstruct gets upset when it sees struct addresspace (which is > > randomized) being assigned to a struct page (which is not randomized): > > > > drivers/net/ethernet/sun/niu.c:3385:12: error: casting from randomized structure pointer type 'struct address_space *' to 'struct page *' > > *link = (struct page *) page->mapping; > > ^ > > > > It looks like niu.c is looking for an in-line place to chain its allocated > > pages together and is overloading the "mapping" member, as it is unused. > > This is very non-standard, and is expected to be cleaned up in the > > future[1], but there is no "correct" way to handle it today. > > > > No meaningful machine code changes result after this change, and source > > readability is improved. > > > > Drop the randstruct exception now that there is no "confusing" cross-type > > assignment. > > > > [1] https://lore.kernel.org/lkml/YnqgjVoMDu5v9PNG@casper.infradead.org/ > > > > Cc: "Matthew Wilcox (Oracle)" > > Cc: Christoph Hellwig > > Cc: "David S. Miller" > > Cc: Jakub Kicinski > > Cc: Paolo Abeni > > Cc: Du Cheng > > Cc: Christophe JAILLET > > Cc: Vlastimil Babka > > Cc: William Kucharski > > Cc: Arnd Bergmann > > Cc: Nathan Chancellor > > Cc: netdev@vger.kernel.org > > Cc: linux-mm@kvack.org > > Cc: linux-hardening@vger.kernel.org > > Signed-off-by: Kees Cook > > I presume you prefer to take this one via your tree too, so: Yeah, that's easiest for the exception removals. > Acked-by: Jakub Kicinski Thanks! -- Kees Cook