From patchwork Tue Sep 15 16:20:49 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Colin King X-Patchwork-Id: 11777223 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 42161746 for ; Tue, 15 Sep 2020 16:21:02 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1FEF220708 for ; Tue, 15 Sep 2020 16:21:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1FEF220708 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=canonical.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E20E76E870; Tue, 15 Sep 2020 16:20:58 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from youngberry.canonical.com (youngberry.canonical.com [91.189.89.112]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0CC0289A59 for ; Tue, 15 Sep 2020 16:20:57 +0000 (UTC) Received: from 1.general.cking.uk.vpn ([10.172.193.212] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1kIDhJ-0007yl-QR; Tue, 15 Sep 2020 16:20:49 +0000 From: Colin King To: Sandy Huang , =?utf-8?q?Heiko_St=C3=BCbner?= , David Airlie , Daniel Vetter , Chris Zhong , Guenter Roeck , Sean Paul , dri-devel@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org Subject: [PATCH] drm/rockchip: cdn-dp: fix sign extension on an int multiply for a u64 result Date: Tue, 15 Sep 2020 17:20:49 +0100 Message-Id: <20200915162049.36434-1-colin.king@canonical.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Colin Ian King The variable bit_per_pix is a u8 and is promoted in the multiplication to an int type and then sign extended to a u64. If the result of the int multiplication is greater than 0x7fffffff then the upper 32 bits will be set to 1 as a result of the sign extension. Avoid this by casting tu_size_reg to u64 to avoid sign extension and also a potential overflow. Addresses-Coverity: ("Unintended sign extension") Fixes: 1a0f7ed3abe2 ("drm/rockchip: cdn-dp: add cdn DP support for rk3399") Signed-off-by: Colin Ian King Reviewed-by: Guenter Roeck --- drivers/gpu/drm/rockchip/cdn-dp-reg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/rockchip/cdn-dp-reg.c b/drivers/gpu/drm/rockchip/cdn-dp-reg.c index 9d2163ef4d6e..33fb4d05c506 100644 --- a/drivers/gpu/drm/rockchip/cdn-dp-reg.c +++ b/drivers/gpu/drm/rockchip/cdn-dp-reg.c @@ -658,7 +658,7 @@ int cdn_dp_config_video(struct cdn_dp_device *dp) */ do { tu_size_reg += 2; - symbol = tu_size_reg * mode->clock * bit_per_pix; + symbol = (u64)tu_size_reg * mode->clock * bit_per_pix; do_div(symbol, dp->max_lanes * link_rate * 8); rem = do_div(symbol, 1000); if (tu_size_reg > 64) {