From nobody Thu Apr 9 04:43:20 2026 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 167C4C4321E for ; Wed, 2 Nov 2022 15:56:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231127AbiKBP4s (ORCPT ); Wed, 2 Nov 2022 11:56:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230150AbiKBP4q (ORCPT ); Wed, 2 Nov 2022 11:56:46 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C24572A70A for ; Wed, 2 Nov 2022 08:56:45 -0700 (PDT) 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 6934461458 for ; Wed, 2 Nov 2022 15:56:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37357C433C1; Wed, 2 Nov 2022 15:56:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667404604; bh=eKbd97vkxuefqY9NLXZOBScngwsvyodqrMGr4osaqpM=; h=From:To:Cc:Subject:Date:From; b=QEeIJzQhBQ0ln9r6jspxi/JHuDxERVJXeR34L8KMxzb/iBI3vxKYohDDJ5qi0SYMh 5birGEcLTZ8O9M+cAd5L5Ya9X0cQ8d/Yc2lBgAYQXjjoi4gcu5d5ocS8PCOoBmYASQ dESAVUO0KimN/Y9WfRtKkArsURnmszVYxZRDWnNUJObyvmCZNSPnvOD6EMl4UUHQnM iisuG7rROiDFJoYFAN3n0/3hrDkgL3OHXAxZpxJaBCQJ3Q+mU4Imo/pQFFQuAYLinl +RbZdgAhoCLLG+O0WCsb/0mva65O5md/nL4ajIjRqRyePp2bYtSPQoyasJZUIOoFsi 6SzHRb+oEOGsQ== From: Nathan Chancellor To: Alain Volmat Cc: dri-devel@lists.freedesktop.org, Nick Desaulniers , Tom Rix , Kees Cook , Sami Tolvanen , llvm@lists.linux.dev, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Nathan Chancellor Subject: [PATCH] drm/sti: Fix return type of sti_{dvo,hda,hdmi}_connector_mode_valid() Date: Wed, 2 Nov 2022 08:56:23 -0700 Message-Id: <20221102155623.3042869-1-nathan@kernel.org> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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/sti/sti_hda.c:637:16: error: incompatible function pointe= r types initializing 'enum drm_mode_status (*)(struct drm_connector *, stru= ct drm_display_mode *)' with an expression of type 'int (struct drm_connect= or *, struct drm_display_mode *)' [-Werror,-Wincompatible-function-pointer-= types-strict] .mode_valid =3D sti_hda_connector_mode_valid, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/gpu/drm/sti/sti_dvo.c:376:16: error: incompatible function pointe= r types initializing 'enum drm_mode_status (*)(struct drm_connector *, stru= ct drm_display_mode *)' with an expression of type 'int (struct drm_connect= or *, struct drm_display_mode *)' [-Werror,-Wincompatible-function-pointer-= types-strict] .mode_valid =3D sti_dvo_connector_mode_valid, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/gpu/drm/sti/sti_hdmi.c:1035:16: error: incompatible function poin= ter types initializing 'enum drm_mode_status (*)(struct drm_connector *, st= ruct drm_display_mode *)' with an expression of type 'int (struct drm_conne= ctor *, struct drm_display_mode *)' [-Werror,-Wincompatible-function-pointe= r-types-strict] .mode_valid =3D sti_hdmi_connector_mode_valid, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ->mode_valid() in 'struct drm_connector_helper_funcs' expects a return type of 'enum drm_mode_status', not 'int'. Adjust the return type of sti_{dvo,hda,hdmi}_connector_mode_valid() to match the prototype's to resolve the warning and CFI failure. Link: https://github.com/ClangBuiltLinux/linux/issues/1750 Signed-off-by: Nathan Chancellor Reviewed-by: Kees Cook --- drivers/gpu/drm/sti/sti_dvo.c | 5 +++-- drivers/gpu/drm/sti/sti_hda.c | 5 +++-- drivers/gpu/drm/sti/sti_hdmi.c | 5 +++-- 3 files changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/sti/sti_dvo.c b/drivers/gpu/drm/sti/sti_dvo.c index b6ee8a82e656..076d5f30a09c 100644 --- a/drivers/gpu/drm/sti/sti_dvo.c +++ b/drivers/gpu/drm/sti/sti_dvo.c @@ -346,8 +346,9 @@ static int sti_dvo_connector_get_modes(struct drm_conne= ctor *connector) =20 #define CLK_TOLERANCE_HZ 50 =20 -static int sti_dvo_connector_mode_valid(struct drm_connector *connector, - struct drm_display_mode *mode) +static enum drm_mode_status +sti_dvo_connector_mode_valid(struct drm_connector *connector, + struct drm_display_mode *mode) { int target =3D mode->clock * 1000; int target_min =3D target - CLK_TOLERANCE_HZ; diff --git a/drivers/gpu/drm/sti/sti_hda.c b/drivers/gpu/drm/sti/sti_hda.c index 03cc401ed593..a53b5a15c2a9 100644 --- a/drivers/gpu/drm/sti/sti_hda.c +++ b/drivers/gpu/drm/sti/sti_hda.c @@ -601,8 +601,9 @@ static int sti_hda_connector_get_modes(struct drm_conne= ctor *connector) =20 #define CLK_TOLERANCE_HZ 50 =20 -static int sti_hda_connector_mode_valid(struct drm_connector *connector, - struct drm_display_mode *mode) +static enum drm_mode_status +sti_hda_connector_mode_valid(struct drm_connector *connector, + struct drm_display_mode *mode) { int target =3D mode->clock * 1000; int target_min =3D target - CLK_TOLERANCE_HZ; diff --git a/drivers/gpu/drm/sti/sti_hdmi.c b/drivers/gpu/drm/sti/sti_hdmi.c index cb82622877d2..09e0cadb6368 100644 --- a/drivers/gpu/drm/sti/sti_hdmi.c +++ b/drivers/gpu/drm/sti/sti_hdmi.c @@ -1004,8 +1004,9 @@ static int sti_hdmi_connector_get_modes(struct drm_co= nnector *connector) =20 #define CLK_TOLERANCE_HZ 50 =20 -static int sti_hdmi_connector_mode_valid(struct drm_connector *connector, - struct drm_display_mode *mode) +static enum drm_mode_status +sti_hdmi_connector_mode_valid(struct drm_connector *connector, + struct drm_display_mode *mode) { int target =3D mode->clock * 1000; int target_min =3D target - CLK_TOLERANCE_HZ; base-commit: 9abf2313adc1ca1b6180c508c25f22f9395cc780 --=20 2.38.1