From patchwork Mon Oct 28 20:08:25 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robin Murphy X-Patchwork-Id: 11216355 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4D9AA139A for ; Mon, 28 Oct 2019 20:08:38 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 2FD30208C0 for ; Mon, 28 Oct 2019 20:08:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2FD30208C0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 038536E9E9; Mon, 28 Oct 2019 20:08:37 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by gabe.freedesktop.org (Postfix) with ESMTP id 615936E9E9 for ; Mon, 28 Oct 2019 20:08:35 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8293531F; Mon, 28 Oct 2019 13:08:34 -0700 (PDT) Received: from e110467-lin.cambridge.arm.com (e110467-lin.cambridge.arm.com [10.1.197.57]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id B4C9F3F71F; Mon, 28 Oct 2019 13:08:33 -0700 (PDT) From: Robin Murphy To: robh@kernel.org, tomeu.vizoso@collabora.com Subject: [PATCH] drm/panfrost: Don't dereference bogus MMU pointers Date: Mon, 28 Oct 2019 20:08:25 +0000 Message-Id: <9a0b09e6b5851f0d4428b72dd6b8b4c0d0ef4206.1572293305.git.robin.murphy@arm.com> X-Mailer: git-send-email 2.21.0.dirty MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, steven.price@arm.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" It seems that killing an application while faults are occurring (particularly with a GPU in FPGA at a whopping 40MHz) can lead to handling a lingering page fault after all the address space contexts have already been freed. In this situation, the LRU list is empty so addr_to_drm_mm_node() ends up dereferencing the list head as if it were a struct panfrost_mmu entry; this leaves "mmu->as" actually pointing at the pfdev->alloc_mask bitmap, which is also empty, and given that the fault has a high likelihood of being in AS0, hilarity ensues. Sadly, the cleanest solution seems to involve another goto. Oh well, at least it's robust... Signed-off-by: Robin Murphy --- drivers/gpu/drm/panfrost/panfrost_mmu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c b/drivers/gpu/drm/panfrost/panfrost_mmu.c index e61984e26e0a..508765f80cfe 100644 --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c @@ -413,11 +413,11 @@ addr_to_drm_mm_node(struct panfrost_device *pfdev, int as, u64 addr) spin_lock(&pfdev->as_lock); list_for_each_entry(mmu, &pfdev->as_lru_list, list) { if (as == mmu->as) - break; + goto found_mmu; } - if (as != mmu->as) - goto out; + goto out; +found_mmu: priv = container_of(mmu, struct panfrost_file_priv, mmu); spin_lock(&priv->mm_lock);