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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D392EE021A for ; Fri, 15 Sep 2023 04:30:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231955AbjIOEaw (ORCPT ); Fri, 15 Sep 2023 00:30:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45226 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231792AbjIOEau (ORCPT ); Fri, 15 Sep 2023 00:30:50 -0400 Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F2EC270C for ; Thu, 14 Sep 2023 21:30:45 -0700 (PDT) Received: by mail-pf1-x42e.google.com with SMTP id d2e1a72fcca58-68fb79ef55eso1570647b3a.0 for ; Thu, 14 Sep 2023 21:30:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1694752245; x=1695357045; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=XsL0E9wvxns4U7l/ZwCaHkG93dEorgZ6k1wpN9ixUXY=; b=DIsqJTf82JyWJW+1mtEnCHlHX8ditJOAKl2Cywbw9IDfq5uBjzayUiv/0aWJpsdrxJ KlecA9RgYU53Xkp5udIoKF+uxbQsymlMDjyUFUlweie7itLUD+WAR9HzA/9RvMRX6+jw n/MPpEJ80XS0QgizDQSobUcehFRSyTVk2A40Q= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694752245; x=1695357045; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=XsL0E9wvxns4U7l/ZwCaHkG93dEorgZ6k1wpN9ixUXY=; b=m8EO8MG0r/bkeBwgusu01R4W6HMm4pCj26KCjY9+w75Z7ItJKKbMxc99qBQOCB7QBX NTz3Po2hQwDmzBjCQMJ5zcVbaj2kuZGHUqQQbXo0oM3TMCGi281eGz/rfNrN3rGHFGCz A1K4qemS0jBg0s7N2WXG+chWCNi9n9eU4HDgZN81JQ2pSbirSeKMiFfgSR/lsvHuzTwy p31Zr5kkx5VtxCxPOint/4iqn1LcFQzCZPIkd43uJseLKCSjuFrwP3gWbgnW1P72p7jM zMxbeomj790B5VEyhMySbkNxkFQI9tVrSTJFKf/AlPnNg5or/w2oRavDCr9uNXltqb7f ndVQ== X-Gm-Message-State: AOJu0YyQxh9ljptIByWEV/shm04sVicFZ6S5W46lkS7twe72rLZZQ3bX qwt1OpmZXbX8Wfqv1XcZ/HpbWA== X-Google-Smtp-Source: AGHT+IHQxJBzE959LD14CEM1tohj88xdcd7+u7zKv8kSGIXuEzf6ekyCP/qKCPCuomlgXxkHpjJDxg== X-Received: by 2002:a05:6a20:3255:b0:14d:6309:fc94 with SMTP id hm21-20020a056a20325500b0014d6309fc94mr747971pzc.36.1694752244954; Thu, 14 Sep 2023 21:30:44 -0700 (PDT) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id a6-20020aa78646000000b0069026841829sm2049947pfo.113.2023.09.14.21.30.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 Sep 2023 21:30:44 -0700 (PDT) Date: Thu, 14 Sep 2023 21:30:43 -0700 From: Kees Cook To: Justin Stitt Cc: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, Xu Panda Subject: Re: [PATCH] drm/modes: refactor deprecated strncpy Message-ID: <202309142129.46C1EAE2E2@keescook> References: <20230914-strncpy-drivers-gpu-drm-drm_modes-c-v1-1-079b532553a3@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230914-strncpy-drivers-gpu-drm-drm_modes-c-v1-1-079b532553a3@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 14, 2023 at 06:08:44PM +0000, Justin Stitt wrote: > `strncpy` is deprecated for use on NUL-terminated destination strings [1]. > > We should prefer more robust and less ambiguous string interfaces. > > A suitable replacement is `strscpy` [2] due to the fact that it guarantees > NUL-termination on the destination buffer and doesn't incur the > performance loss of unnecessarily NUL-padding. How did you decide it didn't need %NUL padding? I suspect it should have it, as I see what looks like full struct copies happening in places: struct drm_mode_modeinfo umode; ... struct drm_property_blob *blob; drm_mode_convert_to_umode(&umode, mode); blob = drm_property_create_blob(crtc->dev, sizeof(umode), &umode); Can you send a v2 using strscpy_pad() instead? Thanks! -Kees -- Kees Cook