From patchwork Mon Jun 20 12:36:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Thomas Hellstrom X-Patchwork-Id: 12887527 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 05A56C43334 for ; Mon, 20 Jun 2022 12:37:16 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 5EBD410E10E; Mon, 20 Jun 2022 12:37:15 +0000 (UTC) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9313810E10E; Mon, 20 Jun 2022 12:37:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655728633; x=1687264633; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=qFwvu1OGOezNEAXE7rT68a715m4aP7a3YO5THxJS9pw=; b=hkb2lCdDj/tnAchZdDZoKV61neM1am996Fy+MkpIgNcf4lamCDFpyvQM EOhMsCzGp76jUQ31c6omObS1NFo3dPQez9CGCK8rt0xuNSrmeUPH58k5N 7lRYK4QAMZN5wNc3L5qMrbe267bbpMHeDAFFu7slGRHio9vxeJRUV+k4B 1eCsb8L7w3UtNU7TYalf1D+K9Lev+bpmHT/rs+ZKslV5238OHvaDe5udV 4xqPjLM+28rPiETozilId+0RlWD+19PW0rsYlxrF6YtAF3LE59AUAp171 Py9aQMHIzwB3efo2oc8YwcbZf4Ycs5bLQK26cIXdja9aRAtcfytFlrn4J w==; X-IronPort-AV: E=McAfee;i="6400,9594,10380"; a="280939792" X-IronPort-AV: E=Sophos;i="5.92,306,1650956400"; d="scan'208";a="280939792" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jun 2022 05:37:12 -0700 X-IronPort-AV: E=Sophos;i="5.92,306,1650956400"; d="scan'208";a="729367457" Received: from ahashmi-mobl.ger.corp.intel.com (HELO thellstr-mobl1.intel.com) ([10.249.254.225]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jun 2022 05:37:10 -0700 From: =?utf-8?q?Thomas_Hellstr=C3=B6m?= To: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org Date: Mon, 20 Jun 2022 14:36:59 +0200 Message-Id: <20220620123659.381772-1-thomas.hellstrom@linux.intel.com> X-Mailer: git-send-email 2.34.3 MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH v2] drm/i915: Fix vm use-after-free in vma destruction X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Matthew Auld Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" In vma destruction, the following race may occur: Thread 1: Thread 2: i915_vma_destroy(); ... list_del_init(vma->vm_link); ... mutex_unlock(vma->vm->mutex); __i915_vm_release(); release_references(); And in release_reference() we dereference vma->vm to get to the vm gt pointer, leading to a use-after free. However, __i915_vm_release() grabs the vm->mutex so the vm won't be destroyed before vma->vm->mutex is released, so extract the gt pointer under the vm->mutex to avoid the vma->vm dereference in release_references(). v2: Fix a typo in the commit message (Andi Shyti) Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/5944 Fixes: e1a7ab4fca ("drm/i915: Remove the vm open count") Cc: Niranjana Vishwanathapura Cc: Matthew Auld Signed-off-by: Thomas Hellström Acked-by: Nirmoy Das Reviewed-by: Andrzej Hajda Reviewed-by: Matthew Auld --- drivers/gpu/drm/i915/i915_vma.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c index 0bffb70b3c5f..04d12f278f57 100644 --- a/drivers/gpu/drm/i915/i915_vma.c +++ b/drivers/gpu/drm/i915/i915_vma.c @@ -1637,10 +1637,10 @@ static void force_unbind(struct i915_vma *vma) GEM_BUG_ON(drm_mm_node_allocated(&vma->node)); } -static void release_references(struct i915_vma *vma, bool vm_ddestroy) +static void release_references(struct i915_vma *vma, struct intel_gt *gt, + bool vm_ddestroy) { struct drm_i915_gem_object *obj = vma->obj; - struct intel_gt *gt = vma->vm->gt; GEM_BUG_ON(i915_vma_is_active(vma)); @@ -1695,11 +1695,12 @@ void i915_vma_destroy_locked(struct i915_vma *vma) force_unbind(vma); list_del_init(&vma->vm_link); - release_references(vma, false); + release_references(vma, vma->vm->gt, false); } void i915_vma_destroy(struct i915_vma *vma) { + struct intel_gt *gt; bool vm_ddestroy; mutex_lock(&vma->vm->mutex); @@ -1707,8 +1708,11 @@ void i915_vma_destroy(struct i915_vma *vma) list_del_init(&vma->vm_link); vm_ddestroy = vma->vm_ddestroy; vma->vm_ddestroy = false; + + /* vma->vm may be freed when releasing vma->vm->mutex. */ + gt = vma->vm->gt; mutex_unlock(&vma->vm->mutex); - release_references(vma, vm_ddestroy); + release_references(vma, gt, vm_ddestroy); } void i915_vma_parked(struct intel_gt *gt)