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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 045E9C433E0 for ; Mon, 3 Aug 2020 20:45:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0283D2086A for ; Mon, 3 Aug 2020 20:45:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=sang-engineering.com header.i=@sang-engineering.com header.b="1McbOKwa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728476AbgHCUpL (ORCPT ); Mon, 3 Aug 2020 16:45:11 -0400 Received: from www.zeus03.de ([194.117.254.33]:46572 "EHLO mail.zeus03.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728346AbgHCUpK (ORCPT ); Mon, 3 Aug 2020 16:45:10 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple; d=sang-engineering.com; h= date:from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=k1; bh=ZhVmGbXvuTacJmIha4DYNPEkfeRI rbClDb5J0Kr9Dno=; b=1McbOKwa16RT6Cm2cNrd30f0pFPY09fOoKY9LtzA5nFu kvqeQdRH+39XiG7wej6WA95wntneFAkZWx2I5RrCE7zkiMPS8X5D9aBdbtm3H3du jqQzCWHdwV9/UBRk1GAly/cgMYoNSuSnXXLcJudX04I0VGynnC4u+gPAY5WZfXY= Received: (qmail 2497905 invoked from network); 3 Aug 2020 22:45:08 +0200 Received: by mail.zeus03.de with ESMTPSA (TLS_AES_256_GCM_SHA384 encrypted, authenticated); 3 Aug 2020 22:45:08 +0200 X-UD-Smtp-Session: l3s3148p1@fwzTNv+riMxQT+F6 Date: Mon, 3 Aug 2020 22:45:07 +0200 From: Wolfram Sang To: Daniel Stodden Cc: linux-i2c@vger.kernel.org, linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH i2c-tools] i2ctransfer: add support for I2C_M_RECV_LEN Message-ID: <20200803204507.GB2488@kunai> Mail-Followup-To: Wolfram Sang , Daniel Stodden , linux-i2c@vger.kernel.org, linux-renesas-soc@vger.kernel.org References: <20200802192842.13527-1-wsa+renesas@sang-engineering.com> <20200802213828.GB13339@kunai> <20200803083823.GA958@kunai> <34A8CC90-0EED-4DD8-89EF-E1B81B7D6DB7@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="dTy3Mrz/UPE2dbVg" Content-Disposition: inline In-Reply-To: <34A8CC90-0EED-4DD8-89EF-E1B81B7D6DB7@gmail.com> Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org --dTy3Mrz/UPE2dbVg Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > If the driver author only looks at __i2_transfer =3D> master_xfer invocat= ions > as employed by i2c_smbus_xfer_emulated, and PEC isn=E2=80=99t used either= , then that > code path let=E2=80=99s you get away with pretty much any msgs[i].len you= come up with. Which explains the patch we are discussing here. I wanted to have a simple way to trigger I2C_M_RECV_LEN from userspace. I am thinking of adding a check to this patch: complain if msg->len is not what we expect and tell people they should report it. --dTy3Mrz/UPE2dbVg Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEOZGx6rniZ1Gk92RdFA3kzBSgKbYFAl8od1AACgkQFA3kzBSg KbbhDBAAst5i5/Z3C6azHsFfqP3+d4C2Yjsm+6nPQw1XSBvpMky08uut2rsCl1xm XyOHZZtjd4HeOUIYfpTl2BoVpbKE16tmrO0sI/WfQdxtHPmNX35HOHRDEvcgqFQS f9RXBbhQEkBGZxClgPmWXtWfxurk3zyK3OtLGTL4KLwIT57O6OVrXhqj099dpKKQ bS/RYtXmmy2HKGiMv9Ty/8/OtVoBqMPpaidBzBYpUGbNU14iG+63njD5wgHzJeBl zS5aY9JQ30IjKqqaLWiqU1hZu2pOQeCUX4wYB3fiWh7JkFd94ELXFgZRHAAOT3gF f4veSjOMeU0fROBlfOq7xpz1Fc+0sd02HnFLsoBid/CYgloT6Ml0AvvEK/Zp7zaZ Y1Q99GYUTTstvsy9f4053K9JuRcofjs4WdZloOFEONTT9O/xQVqXWKMTtdJ0BUvj Ky/74ZvHbxpa4z3nSKD137IaHnV6lHLTloAZBifmL/dk9AVumx9WaCirOkmG7oFY NodashY4Yor8wWxx0Oyyz2jxGHfd7FoYeEUl+3/45lu16NqPvxX0g4JoHY+MzLLV 4PxNiebUGBt035CIsVfiAUz3LLcr+fzitLBi/LdDdwSTVy5dPr/8TKM4StnCmR5m abQIjgUoRd/gnQBk4LimrwPWwIvB6D+vYGR53ybKuzuNoLyUno0= =zb7C -----END PGP SIGNATURE----- --dTy3Mrz/UPE2dbVg--