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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 8DB22FEDA1A for ; Tue, 17 Mar 2026 20:12:26 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 30CC110E48F; Tue, 17 Mar 2026 20:12:26 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="XAu+xAe9"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.20]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7C0E710E1E6; Tue, 17 Mar 2026 20:12:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1773778345; x=1805314345; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=mNwI6kXdR7VYsy+ecKSqi20yTNSIaZRyQCCA0fH8/B4=; b=XAu+xAe9rro0GLE6OWQTnqtoei/yMCkZDj6ae12gD83MrrkzYEY3EwbP chquIy0y+kVAQo44bK/A0J+xHzhduDobNMoxH5WjFaBfggajIo/vZjs8H lU8Qh12k980i8/Yimri38Xv7QAk8Y/53dAPEZPUkcVsTqlliblvI3GGq4 Q/G10XeOSutcdWRImoiw7Ww9aewYXHfFY8gU/7x7yMtakuIGKulLZTG6K QyZIDjFWfWboHuDVPQVhZXT+ISglwfQrLipOiZvskgby1vPMiHVuRpWis pwDek1KRvA1J1Y/jb7j3kwM5C6atURlWx4JNZypnwJep99gnx3U3l+JGZ w==; X-CSE-ConnectionGUID: rnELAKLnTqenQplcs1u4cw== X-CSE-MsgGUID: TIghaDztQ1Ghq8XFfCcI1g== X-IronPort-AV: E=McAfee;i="6800,10657,11732"; a="74523477" X-IronPort-AV: E=Sophos;i="6.23,126,1770624000"; d="scan'208";a="74523477" Received: from orviesa009.jf.intel.com ([10.64.159.149]) by orvoesa112.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2026 13:12:24 -0700 X-CSE-ConnectionGUID: ue86XasPSUmNTCDa3/yZ8A== X-CSE-MsgGUID: 8sH83R47R2WRhYiJuQjxZw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,126,1770624000"; d="scan'208";a="222352497" Received: from krybak-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.246.32]) by orviesa009-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Mar 2026 13:12:17 -0700 From: Jani Nikula To: Gui-Dong Han , gregkh@linuxfoundation.org, dakr@kernel.org, rafael@kernel.org, rodrigo.vivi@intel.com, joonas.lahtinen@linux.intel.com, tursulin@ursulin.net, airlied@gmail.com, simona@ffwll.ch Cc: gustavo.sousa@intel.com, demarchi@kernel.org, jouni.hogander@intel.com, luciano.coelho@intel.com, linux-kernel@vger.kernel.org, driver-core@lists.linux.dev, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-sound@vger.kernel.org, akaieurus@gmail.com, me@ziyao.cc, Gui-Dong Han Subject: Re: [PATCH 4/4] drm/i915/display: initialize string params to empty strings In-Reply-To: <20260317191538.43535-1-hanguidong02@gmail.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs Bertel Jungin Aukio 5, 02600 Espoo, Finland References: <20260317185920.43387-1-hanguidong02@gmail.com> <20260317191538.43535-1-hanguidong02@gmail.com> Date: Tue, 17 Mar 2026 22:12:13 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" On Wed, 18 Mar 2026, Gui-Dong Han wrote: > Passing NULL to debugfs_create_str() causes a NULL pointer dereference > upon reading, and is no longer permitted. Change the default values of > dmc_firmware_path and vbt_firmware to empty strings (""). > > Existing code that consumes these parameters already verifies both > pointer validity and string length, so empty strings are handled > correctly. Furthermore, heap allocation is not required here: these > debugfs parameters are created with strictly read-only permissions > (0400). As a result, the debugfs write operation is never invoked, > meaning the static empty string will not be erroneously freed by > kfree(). > > Fixes: e9913f0bd2e1 ("drm/i915/display: move dmc_firmware_path to display params") > Fixes: 29292bc6cc37 ("drm/i915/display: Move vbt_firmware module parameter under display") > Signed-off-by: Gui-Dong Han > --- > drivers/gpu/drm/i915/display/intel_display_params.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_display_params.h b/drivers/gpu/drm/i915/display/intel_display_params.h > index b95ecf728daa..0a8cad98d480 100644 > --- a/drivers/gpu/drm/i915/display/intel_display_params.h > +++ b/drivers/gpu/drm/i915/display/intel_display_params.h > @@ -23,8 +23,8 @@ struct drm_printer; > * debugfs file > */ > #define INTEL_DISPLAY_PARAMS_FOR_EACH(param) \ > - param(char *, dmc_firmware_path, NULL, 0400) \ > - param(char *, vbt_firmware, NULL, 0400) \ > + param(char *, dmc_firmware_path, "", 0400) \ > + param(char *, vbt_firmware, "", 0400) \ Admittedly this is all very convoluted, but these NULL pointers (or pointers to them) are never passed to debugfs_create_str(). BR, Jani. > param(int, lvds_channel_mode, 0, 0400) \ > param(int, panel_use_ssc, -1, 0600) \ > param(int, vbt_sdvo_panel_type, -1, 0400) \ -- Jani Nikula, Intel