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=-4.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 A4A3DC433DB for ; Sun, 28 Mar 2021 20:43:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 78AD26195E for ; Sun, 28 Mar 2021 20:43:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230526AbhC1Umj (ORCPT ); Sun, 28 Mar 2021 16:42:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39984 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231228AbhC1UmU (ORCPT ); Sun, 28 Mar 2021 16:42:20 -0400 Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB85CC061756 for ; Sun, 28 Mar 2021 13:42:19 -0700 (PDT) Received: by mail-wm1-x335.google.com with SMTP id r10-20020a05600c35cab029010c946c95easo5630665wmq.4 for ; Sun, 28 Mar 2021 13:42:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:cc:references:from:autocrypt:subject:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=ncUmqZv5FjdoR3GFLXteAXsfU0eBF0685dwdt1I8t5A=; b=eycV5Uv/cjGUIAgdiZyrNvlztjedPMZb2hCtosVKBdWOPp6R3G4RLympTOUWkI6GTY 5pjiSf84pBZENLR5suilBHBLwJjeIJT0HGXRLNkz1dJhj/5PXDsbmtI5hmlRNL5WNL0S B4zYBJ34o5h3I2y1Xw239PYaywMWvkLHLqXCBt6QlOXv1EEqecDzNEAKEbW0fScwmUnY RqNm6fGBcUcHdcFdjdwBwYtYKJWxHYWdYMoT8s9cou9cW4P7HlXb3urBUTgPhnAPJKV3 AlaijrHqeu83lV1BVN13wz5yTYFG0PtZ0HDa6VH4nZORXNonHWzy12k591QwqGLU4EDq ZF5g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:autocrypt:subject :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=ncUmqZv5FjdoR3GFLXteAXsfU0eBF0685dwdt1I8t5A=; b=iDzLHcwkpN+5VqlmTRofpmUdPbvD/RZuJ4lyx+Hz/iLlrvGRyluPS8hn+xJNfnH5IG KbjR45/cct38wizA4LndqSlEju3fHG9e7yGcsX1r3P90aKRhf490Yk6dLPQ+d4gMCzb9 U0rVSqzCPV+Vu0jqEhYGkeyAJdvHkwUYXJ1uCEizUXx/5+6E4Up+qx13HXG2HOw/VCNr hF1fAbl9rGDCIiNgJa15UrnKH4NOEiBjixfDn+yuw+w310fr1Oqx3GcfItMntqivdke0 IASngfvWl0LftiD8KtObyJFgDfxOR3oNCnWmALtTawSteVr4ex/WQRICdgPu03hZ1nBf m/pg== X-Gm-Message-State: AOAM532k/rh/UnAkI1Y3O57xXUjSFZx/lZjCzJEaNuAo4EbNYWxU1lAY V8AlxndfM6RWVgAk5fC0ytRnyh9ei/iJDw== X-Google-Smtp-Source: ABdhPJyFFsx+r/5cUu/6jIXxu5ZpYc9NS2HB4LNx+OsZS5foCuJnnnRliBMYFgnq2Rn00dyMKLKWtw== X-Received: by 2002:a7b:cd15:: with SMTP id f21mr21554954wmj.43.1616964137621; Sun, 28 Mar 2021 13:42:17 -0700 (PDT) Received: from [192.168.8.108] ([148.252.129.162]) by smtp.gmail.com with ESMTPSA id i10sm25825834wrs.11.2021.03.28.13.42.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 28 Mar 2021 13:42:17 -0700 (PDT) To: Linus Torvalds , Jens Axboe , Colin Ian King Cc: io-uring , "Eric W. Biederman" References: From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Subject: Re: [GIT PULL] io_uring fixes for 5.12-rc5 Message-ID: Date: Sun, 28 Mar 2021 21:38:14 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 28/03/2021 20:02, Linus Torvalds wrote: > On Sat, Mar 27, 2021 at 6:02 PM Jens Axboe wrote: >> >> - Fix sign extension issue for IORING_OP_PROVIDE_BUFFERS > > I don't think this fixes anything. > > It may change the sign bit, but as far as I can tell, doesn't actually > fix anything at all. You're multiplying a 16-bit value with a signed > 32-bit one. The cast to "unsigned long" makes sure it's done as an > unsigned multiply, but doesn't change anything funcamental. > > - "p->len" is an explictly signed type (__s32). Don't ask me why. > > - the size calculation takes that signed value, turns it into an > "unsigned long" (which sign-extends it), and then does an unsigned > multiply of that nonsensical value > > - that can overflow both in 64-bit and 32-bit (since the 32-bit > signed value has been made an extremely large "unsigned long" > > So there is absolutely nothing "right" about the typing there. Not > before, and not after. The whole cast is entirely meaningless, and > doesn't seem to fix anything. It is basically a random change. > > If you want that calculation to make sense, you need to > > (a) disallow the insane case of signed "len". Most certainly not > sign-extend it to a large unsigned value. > > (b) actually make sure there is no overflow > > because adding a random cast does neither of those things. Agree, thanks for pointing out. Will get it fixed. -- Pavel Begunkov