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=-4.1 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,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 3CABAC433E3 for ; Wed, 22 Jul 2020 19:49:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1183020825 for ; Wed, 22 Jul 2020 19:49:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="rAixs765" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732632AbgGVTtC (ORCPT ); Wed, 22 Jul 2020 15:49:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45268 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732624AbgGVTtC (ORCPT ); Wed, 22 Jul 2020 15:49:02 -0400 Received: from mail-pg1-x543.google.com (mail-pg1-x543.google.com [IPv6:2607:f8b0:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51F32C0619DC for ; Wed, 22 Jul 2020 12:49:02 -0700 (PDT) Received: by mail-pg1-x543.google.com with SMTP id m22so1845082pgv.9 for ; Wed, 22 Jul 2020 12:49:02 -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=jc9E8zZr6hmET+/1UAV9GoyrfO+T1CN2QS4e+oyyTm8=; b=rAixs765IBPwhi4iRRm0EDOTPpj3cLlCciVVmBSzyPvtrWrNcbbKBXn165F/kYpNRm fw7udxhjuDpg5uQWCFtKO7jgxp2Dj9xTQFEsjKSknasPbYV55rB6xwanORW6eAErHsB7 6nTiCQ0WayVFOYY2teP8diiySwG+DXmOweeP6EeF8kEPwnwqUhQRelZme/gft9c95ddK jEckZMjVpHcaZC8LC5RzI30uAfarSZH2erIsenKPppGfLeZRWVI+PGdvyeA5rolVOiu+ TaOJGKGlO+p9Fc2EGhRjMfjtYIAJkvUItOsh91dmygqv+tXNJ3Y+nVO1ptfHPyyvPGuV giRA== 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=jc9E8zZr6hmET+/1UAV9GoyrfO+T1CN2QS4e+oyyTm8=; b=Mes+d5QgNwvDJG/faJyPbynaQv9c3AavctdUIn7U6knq3GJ4GbKHHN0OY/LrJKPA6Z hJ5/BYya8nNZLk/9FWpDsjUNxo1MwY8nUiTV6I7satVPsxiQlw/R+FseI2J/r0n+WV2e xc53HSppwfF0qRyyvv1crJh/t8ZIvaneG3oIF7WVkxdb1KKjn9iwF0GCy92g3RzyiNDF s59nEsKvpHcuXXIa4CXKcelDb0MI75v5TxRtCOKmRGCPqunrZLeGu9mbNmPeMEu3p2h+ sPqAo7WMgcEWbPO4ZVnLKyJaK7CPP0+QZUL8XI+HeunecYxqLUILANOO0wMK2iOWH14G BNng== X-Gm-Message-State: AOAM532nhjsv1Es1iA6QW5CiLPqU4LWE+FavBIKyi9MEqDMQhyfg7HgI ubrTbSZX6HSy4WemBSc6/frNHp//pSHWle6/n1Y= X-Google-Smtp-Source: ABdhPJxCOee+ql6u16gs27imPZWw4sg6bKpt6BgWHIAiyGx2iJH4uBGv8/4pJ9R/PM24VM9IyU93v4eo2xVjiXibBi8= X-Received: by 2002:a63:ce41:: with SMTP id r1mr1239223pgi.203.1595447341900; Wed, 22 Jul 2020 12:49:01 -0700 (PDT) MIME-Version: 1.0 References: <20200722155103.979802-1-jic23@kernel.org> <20200722155103.979802-12-jic23@kernel.org> In-Reply-To: <20200722155103.979802-12-jic23@kernel.org> From: Andy Shevchenko Date: Wed, 22 Jul 2020 22:48:45 +0300 Message-ID: Subject: Re: [PATCH v3 11/27] iio:light:st_uvis25 Fix timestamp alignment and prevent data leak. To: Jonathan Cameron Cc: linux-iio , Lars-Peter Clausen , Peter Meerwald , Jonathan Cameron , Lorenzo Bianconi Content-Type: text/plain; charset="UTF-8" Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Wed, Jul 22, 2020 at 6:53 PM Jonathan Cameron wrote: > > From: Jonathan Cameron > > One of a class of bugs pointed out by Lars in a recent review. > iio_push_to_buffers_with_timestamp assumes the buffer used is aligned > to the size of the timestamp (8 bytes). This is not guaranteed in > this driver which uses an array of smaller elements on the stack. > As Lars also noted this anti pattern can involve a leak of data to > userspace and that indeed can happen here. We close both issues by > moving to a suitable structure in the iio_priv() > > This data is allocated with kzalloc so no data can leak apart > from previous readings. > > A local unsigned int variable is used for the regmap call so it > is clear there is no potential issue with writing into the padding > of the structure. ... > + u8 chan; > + hw->scan.chan = val & 0xFF; 0xFF is not needed. -- With Best Regards, Andy Shevchenko