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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 2A810C433E9 for ; Mon, 11 Jan 2021 12:57:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E19FC2250E for ; Mon, 11 Jan 2021 12:57:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727639AbhAKM5r (ORCPT ); Mon, 11 Jan 2021 07:57:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45994 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727114AbhAKM5r (ORCPT ); Mon, 11 Jan 2021 07:57:47 -0500 Received: from michel.telenet-ops.be (michel.telenet-ops.be [IPv6:2a02:1800:110:4::f00:18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0864C061786 for ; Mon, 11 Jan 2021 04:57:06 -0800 (PST) Received: from ramsan.of.borg ([84.195.186.194]) by michel.telenet-ops.be with bizsmtp id FQx42400V4C55Sk06Qx4bv; Mon, 11 Jan 2021 13:57:05 +0100 Received: from rox.of.borg ([192.168.97.57]) by ramsan.of.borg with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1kywkp-002prj-TH; Mon, 11 Jan 2021 13:57:03 +0100 Received: from geert by rox.of.borg with local (Exim 4.93) (envelope-from ) id 1kywkp-001VrE-AU; Mon, 11 Jan 2021 13:57:03 +0100 From: Geert Uytterhoeven To: Andrzej Hajda , Neil Armstrong Cc: Laurent Pinchart , Jonas Karlman , Jernej Skrabec , David Airlie , Daniel Vetter , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH] drm/bridge: nwl-dsi: Avoid potential multiplication overflow on 32-bit Date: Mon, 11 Jan 2021 13:57:02 +0100 Message-Id: <20210111125702.360745-1-geert+renesas@glider.be> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As nwl_dsi.lanes is u32, and NSEC_PER_SEC is 1000000000L, the second multiplication in dsi->lanes * 8 * NSEC_PER_SEC will overflow on a 32-bit platform. Fix this by making the constant unsigned long long, forcing 64-bit arithmetic. While iMX8 is arm64, this driver is currently used on 64-bit platforms only, where long is 64-bit, so this cannot happen. But the issue may start to happen when the driver is reused for a 32-bit SoC, or when code is copied for a new driver. Signed-off-by: Geert Uytterhoeven --- Compile-tested only. --- drivers/gpu/drm/bridge/nwl-dsi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c index 66b67402f1acd57d..a8da3081efdcc84e 100644 --- a/drivers/gpu/drm/bridge/nwl-dsi.c +++ b/drivers/gpu/drm/bridge/nwl-dsi.c @@ -195,7 +195,7 @@ static u32 ps2bc(struct nwl_dsi *dsi, unsigned long long ps) u32 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format); return DIV64_U64_ROUND_UP(ps * dsi->mode.clock * bpp, - dsi->lanes * 8 * NSEC_PER_SEC); + dsi->lanes * 8ULL * NSEC_PER_SEC); } /* -- 2.25.1