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 89FF6C46467 for ; Mon, 16 Jan 2023 17:13:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233429AbjAPRND (ORCPT ); Mon, 16 Jan 2023 12:13:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234369AbjAPRMV (ORCPT ); Mon, 16 Jan 2023 12:12:21 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 978302B612 for ; Mon, 16 Jan 2023 08:52:31 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 34BF761086 for ; Mon, 16 Jan 2023 16:52:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 477B0C433F0; Mon, 16 Jan 2023 16:52:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673887950; bh=75OkdS2wjJbCjhbZkaVkV32jCHTDz4lKQ3IPNDv16VI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bEVAweBppITeKI0llxiuCLizffXAp95V7fmhs9156r5EuOGysDzrNiQfr6/62Hvpd rZebBRNvOudF3+Wzl7vyaKOMCau19Er4PG46/+lFAG8yPcYa8ul8qEwlzpNUV2fq4O k27gUzal/7xlKZ3f7SnqIiydwCjovUN6ME8Vgnaw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sami Tolvanen , Nathan Chancellor , Kees Cook , Sasha Levin Subject: [PATCH 4.19 344/521] drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid() Date: Mon, 16 Jan 2023 16:50:06 +0100 Message-Id: <20230116154902.536635683@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230116154847.246743274@linuxfoundation.org> References: <20230116154847.246743274@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nathan Chancellor [ Upstream commit 96d845a67b7e406cfed7880a724c8ca6121e022e ] With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), indirect call targets are validated against the expected function pointer prototype to make sure the call target is valid to help mitigate ROP attacks. If they are not identical, there is a failure at run time, which manifests as either a kernel panic or thread getting killed. A proposed warning in clang aims to catch these at compile time, which reveals: drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c:74:16: error: incompatible function pointer types initializing 'enum drm_mode_status (*)(struct drm_connector *, struct drm_display_mode *)' with an expression of type 'int (struct drm_connector *, struct drm_display_mode *)' [-Werror,-Wincompatible-function-pointer-types-strict] .mode_valid = fsl_dcu_drm_connector_mode_valid, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1 error generated. ->mode_valid() in 'struct drm_connector_helper_funcs' expects a return type of 'enum drm_mode_status', not 'int'. Adjust the return type of fsl_dcu_drm_connector_mode_valid() to match the prototype's to resolve the warning and CFI failure. Link: https://github.com/ClangBuiltLinux/linux/issues/1750 Reported-by: Sami Tolvanen Signed-off-by: Nathan Chancellor Reviewed-by: Kees Cook Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20221102154215.78059-1-nathan@kernel.org Signed-off-by: Sasha Levin --- drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c index 2298ed2a9e1c..3c8c4a820e95 100644 --- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c +++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c @@ -83,8 +83,9 @@ static int fsl_dcu_drm_connector_get_modes(struct drm_connector *connector) return num_modes; } -static int fsl_dcu_drm_connector_mode_valid(struct drm_connector *connector, - struct drm_display_mode *mode) +static enum drm_mode_status +fsl_dcu_drm_connector_mode_valid(struct drm_connector *connector, + struct drm_display_mode *mode) { if (mode->hdisplay & 0xf) return MODE_ERROR; -- 2.35.1