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=-0.8 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 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 2A07CCA9EA0 for ; Sun, 20 Oct 2019 06:06:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BEE6D21D80 for ; Sun, 20 Oct 2019 06:06:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Wy52xd07" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BEE6D21D80 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 210978E0005; Sun, 20 Oct 2019 02:06:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1C0468E0003; Sun, 20 Oct 2019 02:06:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0D7338E0005; Sun, 20 Oct 2019 02:06:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0220.hostedemail.com [216.40.44.220]) by kanga.kvack.org (Postfix) with ESMTP id E0D628E0003 for ; Sun, 20 Oct 2019 02:06:56 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id 40485180ACF76 for ; Sun, 20 Oct 2019 06:06:56 +0000 (UTC) X-FDA: 76063129632.02.crown51_599f4a885083f X-HE-Tag: crown51_599f4a885083f X-Filterd-Recvd-Size: 3496 Received: from mail-ot1-f68.google.com (mail-ot1-f68.google.com [209.85.210.68]) by imf17.hostedemail.com (Postfix) with ESMTP for ; Sun, 20 Oct 2019 06:06:55 +0000 (UTC) Received: by mail-ot1-f68.google.com with SMTP id m19so8410651otp.1 for ; Sat, 19 Oct 2019 23:06:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=YCK09w6PWU3uSu7DLwK1iOj9r8NGNR+mR7i729KtO90=; b=Wy52xd07pgpnE6lyPI6PxBww3Zh9ymaVHCiql7MqKwXaQ7SgMR2MNOhWrT9dPupoDs NZ50DC7P0cDNGGGyE0T7iWOMI5eZhFmtT2L+hk7LylL6LaIlxTIDgWlUAeUFwoUA7p+j i4DGkxX03Tct9YSIb42M3v6pWb/6/9yGsDCkm852oX/Ic2A+OPdUrBCZizlaxCGKmv1F QilyEiqE33EfzX+n8ZTSUuKHAffANTDDVHiU1ZeE6jfu48v95mKBGFCSGiTBJidaETiR 94Iv0c9pOy2YAQhlA9Na9rmZVMzpi3Vuj7DoAi3P8v7kcz1AEnVnZgybM0Foe8e03OTc hGyg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=YCK09w6PWU3uSu7DLwK1iOj9r8NGNR+mR7i729KtO90=; b=nozV19gPQ80/C51MUj1Wxl55Yo4RwNRIU3QRDp9bk17ZEjRbo+292zcedr7Oy406+D 17Ho66bzYViiJxi5GPiDPHcCI/fQvV5zy2SE+RCBhijPIERj4TEC+dgddgv4qfNcyS1F ZS5gaXLrmhlHWaLW1YT2zAzxRQ/9Cmvxc1iYwAPIE1mFUlzG8tB401ayEN2UDUc8xOnj d/5VcZfun01YjUupkd2qP/sP40tkXcxKX06YcH7FhnP2FUiDg6QJlttFwetPLKPHVKt9 U1jKDB+9y07kBkSw2NbAGRL5/y58QwzI0DQdIH3SVWQX420HI7c8Oek9hvjdtmK4i3jC HP2Q== X-Gm-Message-State: APjAAAUQBcySF4P+H5E+DdGlzq2x71EJSXm7ibPIuBU4wgIhM2MWblXu ONK0N0DkooJMya++xboJILd3AnjOxmUAbzMAIo8= X-Google-Smtp-Source: APXvYqwJE3ZvYgE+VEd+R8rFhmp8PG/+65EdbgKNxRUva5Hj0LB2yjJy3dvKhuHxAWhHWtsjyKyBfDqZCeuA3uyqYK0= X-Received: by 2002:a05:6830:58:: with SMTP id d24mr14372911otp.128.1571551614997; Sat, 19 Oct 2019 23:06:54 -0700 (PDT) MIME-Version: 1.0 References: <20191010103151.7708-1-mayhs11saini@gmail.com> <20191010174413.GT32665@bombadil.infradead.org> In-Reply-To: <20191010174413.GT32665@bombadil.infradead.org> From: Shyam Saini Date: Sun, 20 Oct 2019 11:36:42 +0530 Message-ID: Subject: Re: [PATCH] slab: Redefine ZERO_SIZE_PTR to include ERR_PTR range To: Matthew Wilcox , Christopher Lameter Cc: linux-mm , Kernel Hardening , Kees Cook Content-Type: text/plain; charset="UTF-8" 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: Hi Matthew, Christopher, > > > This will help error related to ERR_PTR stand out better. > > > > Maybe make ZERO_SIZE_PTR an ERRNO value instead? Then allow ERR_PTRs to be > > used instead of ZERO_SIZE_PTRs > > > > ERRNO_ZERO_OBJECT > > > > or something like that? > > I was wondering about something like that too, but allocating zero bytes > isn't actually an error, and if we have code that does something like: > > void *p = my_funky_alloc(size, ...); > > if (IS_ERR(p)) > return PTR_ERR(p); > > then we might get this errno returned to userspace. > > The change is definitely worth thinking about. Any further comments on this ? Please let me know. Thanks!!