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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 BD34EC3279B for ; Wed, 4 Jul 2018 13:22:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 81A0E208A1 for ; Wed, 4 Jul 2018 13:22:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 81A0E208A1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=embeddedor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753304AbeGDNWo (ORCPT ); Wed, 4 Jul 2018 09:22:44 -0400 Received: from gateway36.websitewelcome.com ([192.185.193.12]:39376 "EHLO gateway36.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752732AbeGDNWn (ORCPT ); Wed, 4 Jul 2018 09:22:43 -0400 Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway36.websitewelcome.com (Postfix) with ESMTP id A9A14400DA8BF for ; Wed, 4 Jul 2018 07:23:29 -0500 (CDT) Received: from gator4166.hostgator.com ([108.167.133.22]) by cmsmtp with SMTP id ahjcf226IBcCXahjsflMuQ; Wed, 04 Jul 2018 08:22:42 -0500 X-Authority-Reason: nr=8 Received: from [189.250.65.56] (port=55390 helo=embeddedor) by gator4166.hostgator.com with esmtpa (Exim 4.91) (envelope-from ) id 1fahjb-003auB-Pd; Wed, 04 Jul 2018 08:22:15 -0500 Date: Wed, 4 Jul 2018 08:22:11 -0500 From: "Gustavo A. R. Silva" To: Michel =?iso-8859-1?Q?D=E4nzer?= , Alex Deucher , Christian =?iso-8859-1?Q?K=F6nig?= , "David (ChunMing) Zhou" , David Airlie Cc: amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH v2] drm/amd/display/dc/dce: Fix multiple potential integer overflows Message-ID: <20180704132211.GA6764@embeddedor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit User-Agent: Mutt/1.5.24 (2015-08-30) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 189.250.65.56 X-Source-L: No X-Exim-ID: 1fahjb-003auB-Pd X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [189.250.65.56]:55390 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 11 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add suffix ULL to constant 5 and cast variables target_pix_clk_khz and feedback_divider to uint64_t in order to avoid multiple potential integer overflows and give the compiler complete information about the proper arithmetic to use. Notice that such constant and variables are used in contexts that expect expressions of type uint64_t (64 bits, unsigned). The current casts to uint64_t effectively apply to each expression as a whole, but they do not prevent them from being evaluated using 32-bit arithmetic instead of 64-bit arithmetic. Also, once the expressions are properly evaluated using 64-bit arithmentic, there is no need for the parentheses that enclose them. Addresses-Coverity-ID: 1460245 ("Unintentional integer overflow") Addresses-Coverity-ID: 1460286 ("Unintentional integer overflow") Addresses-Coverity-ID: 1460401 ("Unintentional integer overflow") Fixes: 4562236b3bc0 ("drm/amd/dc: Add dc display driver (v2)") Signed-off-by: Gustavo A. R. Silva --- Changes in v2: - Add suffix ULL to constant 5 instead of UL. Thanks to Michel Dänzer for pointing this out. drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c index 88b09dd..ca13775 100644 --- a/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c +++ b/drivers/gpu/drm/amd/display/dc/dce/dce_clock_source.c @@ -133,7 +133,7 @@ static bool calculate_fb_and_fractional_fb_divider( uint64_t feedback_divider; feedback_divider = - (uint64_t)(target_pix_clk_khz * ref_divider * post_divider); + (uint64_t)target_pix_clk_khz * ref_divider * post_divider; feedback_divider *= 10; /* additional factor, since we divide by 10 afterwards */ feedback_divider *= (uint64_t)(calc_pll_cs->fract_fb_divider_factor); @@ -145,8 +145,8 @@ static bool calculate_fb_and_fractional_fb_divider( * of fractional feedback decimal point and the fractional FB Divider precision * is 2 then the equation becomes (ullfeedbackDivider + 5*100) / (10*100))*/ - feedback_divider += (uint64_t) - (5 * calc_pll_cs->fract_fb_divider_precision_factor); + feedback_divider += 5ULL * + calc_pll_cs->fract_fb_divider_precision_factor; feedback_divider = div_u64(feedback_divider, calc_pll_cs->fract_fb_divider_precision_factor * 10); @@ -203,8 +203,8 @@ static bool calc_fb_divider_checking_tolerance( &fract_feedback_divider); /*Actual calculated value*/ - actual_calc_clk_khz = (uint64_t)(feedback_divider * - calc_pll_cs->fract_fb_divider_factor) + + actual_calc_clk_khz = (uint64_t)feedback_divider * + calc_pll_cs->fract_fb_divider_factor + fract_feedback_divider; actual_calc_clk_khz *= calc_pll_cs->ref_freq_khz; actual_calc_clk_khz = -- 2.7.4