From patchwork Wed Apr 17 14:56:46 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Dixit, Ashutosh" X-Patchwork-Id: 13633502 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 203AAC04FFF for ; Wed, 17 Apr 2024 14:57:03 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B8EDD1135E9; Wed, 17 Apr 2024 14:57:00 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="UXKaY1X4"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) by gabe.freedesktop.org (Postfix) with ESMTPS id DBCDB1135E0; Wed, 17 Apr 2024 14:56:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1713365818; x=1744901818; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=8BRT7hTgisDDTL7pOfQtyyDPYIkpSERJOh3aEbL+wdo=; b=UXKaY1X43JYptgs6iajtVTBqmCRpDv+uW2jn9WwqHJlQm9EbX8h75mPk gmTXC44/bOMLHMPGcqlOAYBXEFFlH+XP8o/AotcneVy+4ogxyAIvnsmbx xzCVuYwRYq5b1ZQxizvvVz2dS6Q1CShdS7sWWX//unzkFO/wA4rbT//Dq nrFNOXIGvSEScTBhM91u439hSXt1Kh2ypdIP1K9aYKi0joT68XvKLX66A AggCJyzvli4uYlzhpl8kW0JIH3/HUUpCSfZgXYZuNRJjIK2+tHRfDrVGF t76/cfdGis+0WQCrVxXN3si7224BJ1ol2fdaJCzL8DGm60EhRwVckQ3Jd g==; X-CSE-ConnectionGUID: CP73YxHMSpebh8E01r5ROw== X-CSE-MsgGUID: 8NIyjIcSS+mMDoPYY+b0Gg== X-IronPort-AV: E=McAfee;i="6600,9927,11046"; a="20010177" X-IronPort-AV: E=Sophos;i="6.07,209,1708416000"; d="scan'208";a="20010177" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Apr 2024 07:56:55 -0700 X-CSE-ConnectionGUID: JZSHScUcRe6tgbaRGDc7ZA== X-CSE-MsgGUID: RlQMDcGcRGGGr5E5wPSQOw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.07,209,1708416000"; d="scan'208";a="53863120" Received: from orsosgc001.jf.intel.com ([10.165.21.138]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Apr 2024 07:56:51 -0700 From: Ashutosh Dixit To: intel-gfx@lists.freedesktop.org Cc: Badal Nilawar , Andi Shyti , =?utf-8?b?VmlsbGUgU3lyasOkbMOk?= , Rodrigo Vivi , Jani Nikula , linux-hwmon@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [PATCH] drm/i915/hwmon: Get rid of devm Date: Wed, 17 Apr 2024 07:56:46 -0700 Message-ID: <20240417145646.793223-1-ashutosh.dixit@intel.com> X-Mailer: git-send-email 2.41.0 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" When both hwmon and hwmon drvdata (on which hwmon depends) are device managed resources, the expectation, on device unbind, is that hwmon will be released before drvdata. However, in i915 there are two separate code paths, which both release either drvdata or hwmon and either can be released before the other. These code paths (for device unbind) are as follows (see also the bug referenced below): Call Trace: release_nodes+0x11/0x70 devres_release_group+0xb2/0x110 component_unbind_all+0x8d/0xa0 component_del+0xa5/0x140 intel_pxp_tee_component_fini+0x29/0x40 [i915] intel_pxp_fini+0x33/0x80 [i915] i915_driver_remove+0x4c/0x120 [i915] i915_pci_remove+0x19/0x30 [i915] pci_device_remove+0x32/0xa0 device_release_driver_internal+0x19c/0x200 unbind_store+0x9c/0xb0 and Call Trace: release_nodes+0x11/0x70 devres_release_all+0x8a/0xc0 device_unbind_cleanup+0x9/0x70 device_release_driver_internal+0x1c1/0x200 unbind_store+0x9c/0xb0 This means that in i915, if use devm, we cannot gurantee that hwmon will always be released before drvdata. Which means that we have a uaf if hwmon sysfs is accessed when drvdata has been released but hwmon hasn't. The only way out of this seems to be do get rid of devm_ and release/free everything explicitly during device unbind. v2: Change commit message and other minor code changes v3: Cleanup from i915_hwmon_register on error (Armin Wolf) v4: Eliminate potential static analyzer warning (Rodrigo) Eliminate fetch_and_zero (Jani) v5: Restore previous logic for ddat_gt->hwmon_dev error return (Andi) Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/10366 Reviewed-by: Rodrigo Vivi Signed-off-by: Ashutosh Dixit Reviewed-by: Andi Shyti --- drivers/gpu/drm/i915/i915_hwmon.c | 46 +++++++++++++++++++++---------- 1 file changed, 32 insertions(+), 14 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_hwmon.c b/drivers/gpu/drm/i915/i915_hwmon.c index b758fd110c20..c0662a022f59 100644 --- a/drivers/gpu/drm/i915/i915_hwmon.c +++ b/drivers/gpu/drm/i915/i915_hwmon.c @@ -793,7 +793,7 @@ void i915_hwmon_register(struct drm_i915_private *i915) if (!IS_DGFX(i915)) return; - hwmon = devm_kzalloc(dev, sizeof(*hwmon), GFP_KERNEL); + hwmon = kzalloc(sizeof(*hwmon), GFP_KERNEL); if (!hwmon) return; @@ -819,14 +819,12 @@ void i915_hwmon_register(struct drm_i915_private *i915) hwm_get_preregistration_info(i915); /* hwmon_dev points to device hwmon */ - hwmon_dev = devm_hwmon_device_register_with_info(dev, ddat->name, - ddat, - &hwm_chip_info, - hwm_groups); - if (IS_ERR(hwmon_dev)) { - i915->hwmon = NULL; - return; - } + hwmon_dev = hwmon_device_register_with_info(dev, ddat->name, + ddat, + &hwm_chip_info, + hwm_groups); + if (IS_ERR(hwmon_dev)) + goto err; ddat->hwmon_dev = hwmon_dev; @@ -839,16 +837,36 @@ void i915_hwmon_register(struct drm_i915_private *i915) if (!hwm_gt_is_visible(ddat_gt, hwmon_energy, hwmon_energy_input, 0)) continue; - hwmon_dev = devm_hwmon_device_register_with_info(dev, ddat_gt->name, - ddat_gt, - &hwm_gt_chip_info, - NULL); + hwmon_dev = hwmon_device_register_with_info(dev, ddat_gt->name, + ddat_gt, + &hwm_gt_chip_info, + NULL); if (!IS_ERR(hwmon_dev)) ddat_gt->hwmon_dev = hwmon_dev; } + return; +err: + i915_hwmon_unregister(i915); } void i915_hwmon_unregister(struct drm_i915_private *i915) { - fetch_and_zero(&i915->hwmon); + struct i915_hwmon *hwmon = i915->hwmon; + struct intel_gt *gt; + int i; + + if (!hwmon) + return; + + for_each_gt(gt, i915, i) + if (hwmon->ddat_gt[i].hwmon_dev) + hwmon_device_unregister(hwmon->ddat_gt[i].hwmon_dev); + + if (hwmon->ddat.hwmon_dev) + hwmon_device_unregister(hwmon->ddat.hwmon_dev); + + mutex_destroy(&hwmon->hwmon_lock); + + kfree(i915->hwmon); + i915->hwmon = NULL; }