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 X-Spam-Level: X-Spam-Status: No, score=-11.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2BB9C11F66 for ; Wed, 14 Jul 2021 16:49:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D715C61279 for ; Wed, 14 Jul 2021 16:49:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236357AbhGNQwM (ORCPT ); Wed, 14 Jul 2021 12:52:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:51438 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229611AbhGNQwL (ORCPT ); Wed, 14 Jul 2021 12:52:11 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id B302D613C3; Wed, 14 Jul 2021 16:49:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1626281359; bh=6SKB3Qqjs+EC5rQxtbZljNFZlyLM4HZOJZxqpbfl9sM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Ko/UfbhD+PKfNZ3iK4ym6LzrxkwTJIAnlAs+qXdzedMZaGQBceXrGL4yO3Mhi8Yui vMOTVVJx+4Ujke2mPgfBk3Ht3ixeEAIiueMcl+Mt3nZdEGKe/obO9fAbsIwGZd2S1E wlHDb7pZo4ORM9aKt7vjHyClabpj5MHNp1aihZ0eiiUfnZphY1Cf8Si2OtplBMmvoA FklATVbj/QyXl8hG1qWEX00mxNkUQ0OdAccH8p4pfKml6iQ2yveG5hqAcabY/0PnHT ShhjQGUDah6fa1UE1UZsYnAqBBPNlHHBWN0dRxflqSplK04t3uzsQ1hpgqx1ZY+qSN 8z4l8b9ME85bA== Date: Wed, 14 Jul 2021 12:49:18 -0400 From: Sasha Levin To: Pavel Machek Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Xie Yongji , Gerd Hoffmann , dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH AUTOSEL 4.4 08/31] drm/virtio: Fixes a potential NULL pointer dereference on probe failure Message-ID: References: <20210706112931.2066397-1-sashal@kernel.org> <20210706112931.2066397-8-sashal@kernel.org> <20210712215937.GA9488@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20210712215937.GA9488@amd> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 12, 2021 at 11:59:37PM +0200, Pavel Machek wrote: >Hi! > >> From: Xie Yongji >> >> [ Upstream commit 17f46f488a5d82c5568e6e786cd760bba1c2ee09 ] >> >> The dev->dev_private might not be allocated if virtio_gpu_pci_quirk() >> or virtio_gpu_init() failed. In this case, we should avoid the cleanup >> in virtio_gpu_release(). > >The check is in wrong place at least in 4.4: > >> +++ b/drivers/gpu/drm/virtio/virtgpu_kms.c >> @@ -257,6 +257,9 @@ int virtio_gpu_driver_unload(struct drm_device *dev) >> flush_work(&vgdev->config_changed_work); >> vgdev->vdev->config->del_vqs(vgdev->vdev); >> >> + if (!vgdev) >> + return; >> + > >Pointer is dereferenced before being tested. Heh, yes, thanks for catching that. I'll drop it for now and rework it next week. -- Thanks, Sasha