From patchwork Tue Nov 1 06:51:56 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yuan Can X-Patchwork-Id: 13026692 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 28197FA373D for ; Tue, 1 Nov 2022 06:54:34 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B245810E16C; Tue, 1 Nov 2022 06:54:32 +0000 (UTC) Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by gabe.freedesktop.org (Postfix) with ESMTPS id CB9AB88FBD for ; Tue, 1 Nov 2022 06:54:28 +0000 (UTC) Received: from dggpeml500024.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4N1gjr3mxMz15MBv; Tue, 1 Nov 2022 14:54:24 +0800 (CST) Received: from huawei.com (10.175.112.208) by dggpeml500024.china.huawei.com (7.185.36.10) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 1 Nov 2022 14:54:25 +0800 From: Yuan Can To: , , , , , , , Subject: [PATCH 2/2] drm/vkms: Fix null-ptr-deref in vkms_release() Date: Tue, 1 Nov 2022 06:51:56 +0000 Message-ID: <20221101065156.41584-3-yuancan@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20221101065156.41584-1-yuancan@huawei.com> References: <20221101065156.41584-1-yuancan@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.112.208] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpeml500024.china.huawei.com (7.185.36.10) X-CFilter-Loop: Reflected 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: , Cc: yuancan@huawei.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" A null-ptr-deref is triggered when it tries to destroy the workqueue in vkms->output.composer_workq in vkms_release(). KASAN: null-ptr-deref in range [0x0000000000000118-0x000000000000011f] CPU: 5 PID: 17193 Comm: modprobe Not tainted 6.0.0-11331-gd465bff130bf #24 RIP: 0010:destroy_workqueue+0x2f/0x710 ... Call Trace: ? vkms_config_debugfs_init+0x50/0x50 [vkms] __devm_drm_dev_alloc+0x15a/0x1c0 [drm] vkms_init+0x245/0x1000 [vkms] do_one_initcall+0xd0/0x4f0 do_init_module+0x1a4/0x680 load_module+0x6249/0x7110 __do_sys_finit_module+0x140/0x200 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 The reason is that an OOM happened which triggers the destroy of the workqueue, however, the workqueue is alloced in the later process, thus a null-ptr-deref happened. A simple call graph is shown as below: vkms_init() vkms_create() devm_drm_dev_alloc() __devm_drm_dev_alloc() devm_drm_dev_init() devm_add_action_or_reset() devm_add_action() # an error happened devm_drm_dev_init_release() drm_dev_put() kref_put() drm_dev_release() vkms_release() destroy_workqueue() # null-ptr-deref happened vkms_modeset_init() vkms_output_init() vkms_crtc_init() # where the workqueue get allocated Fix this by checking if composer_workq is NULL before passing it to the destroy_workqueue() in vkms_release(). Fixes: 6c234fe37c57 ("drm/vkms: Implement CRC debugfs API") Signed-off-by: Yuan Can Reviewed-by: Melissa Wen --- drivers/gpu/drm/vkms/vkms_drv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c index dfe983eaa07f..f716c5796f5f 100644 --- a/drivers/gpu/drm/vkms/vkms_drv.c +++ b/drivers/gpu/drm/vkms/vkms_drv.c @@ -57,7 +57,8 @@ static void vkms_release(struct drm_device *dev) { struct vkms_device *vkms = drm_device_to_vkms_device(dev); - destroy_workqueue(vkms->output.composer_workq); + if (vkms->output.composer_workq) + destroy_workqueue(vkms->output.composer_workq); } static void vkms_atomic_commit_tail(struct drm_atomic_state *old_state)