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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 E7310C04ABB for ; Thu, 13 Sep 2018 13:31:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A443820854 for ; Thu, 13 Sep 2018 13:31:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A443820854 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728173AbeIMSl0 (ORCPT ); Thu, 13 Sep 2018 14:41:26 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:58448 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727127AbeIMSl0 (ORCPT ); Thu, 13 Sep 2018 14:41:26 -0400 Received: from localhost (ip-213-127-77-73.ip.prioritytelecom.net [213.127.77.73]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id DE931D16; Thu, 13 Sep 2018 13:31:55 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Greg Hackmann , Laura Abbott Subject: [PATCH 4.4 02/60] staging: android: ion: fix ION_IOC_{MAP,SHARE} use-after-free Date: Thu, 13 Sep 2018 15:30:09 +0200 Message-Id: <20180913131745.390423347@linuxfoundation.org> X-Mailer: git-send-email 2.19.0 In-Reply-To: <20180913131745.261413581@linuxfoundation.org> References: <20180913131745.261413581@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Greg Hackmann The ION_IOC_{MAP,SHARE} ioctls drop and reacquire client->lock several times while operating on one of the client's ion_handles. This creates windows where userspace can call ION_IOC_FREE on the same client with the same handle, and effectively make the kernel drop its own reference. For example: - thread A: ION_IOC_ALLOC creates an ion_handle with refcount 1 - thread A: starts ION_IOC_MAP and increments the refcount to 2 - thread B: ION_IOC_FREE decrements the refcount to 1 - thread B: ION_IOC_FREE decrements the refcount to 0 and frees the handle - thread A: continues ION_IOC_MAP with a dangling ion_handle * to freed memory Fix this by holding client->lock for the duration of ION_IOC_{MAP,SHARE}, preventing the concurrent ION_IOC_FREE. Also remove ion_handle_get_by_id(), since there's literally no way to use it safely. This patch is applied on top of 4.4.y, and applies to older kernels too. 4.9.y was fixed separately. Kernels 4.12 and later are unaffected, since all the underlying ion_handle infrastructure has been ripped out. Cc: stable@vger.kernel.org # v4.4- Signed-off-by: Greg Hackmann Acked-by: Laura Abbott Signed-off-by: Greg Kroah-Hartman --- v2: remove Change-Id line from commit message drivers/staging/android/ion/ion.c | 60 +++++++++++++++++++++++--------------- 1 file changed, 37 insertions(+), 23 deletions(-) --- a/drivers/staging/android/ion/ion.c +++ b/drivers/staging/android/ion/ion.c @@ -449,18 +449,6 @@ static struct ion_handle *ion_handle_get return ERR_PTR(-EINVAL); } -struct ion_handle *ion_handle_get_by_id(struct ion_client *client, - int id) -{ - struct ion_handle *handle; - - mutex_lock(&client->lock); - handle = ion_handle_get_by_id_nolock(client, id); - mutex_unlock(&client->lock); - - return handle; -} - static bool ion_handle_validate(struct ion_client *client, struct ion_handle *handle) { @@ -1138,24 +1126,28 @@ static struct dma_buf_ops dma_buf_ops = .kunmap = ion_dma_buf_kunmap, }; -struct dma_buf *ion_share_dma_buf(struct ion_client *client, - struct ion_handle *handle) +static struct dma_buf *__ion_share_dma_buf(struct ion_client *client, + struct ion_handle *handle, + bool lock_client) { DEFINE_DMA_BUF_EXPORT_INFO(exp_info); struct ion_buffer *buffer; struct dma_buf *dmabuf; bool valid_handle; - mutex_lock(&client->lock); + if (lock_client) + mutex_lock(&client->lock); valid_handle = ion_handle_validate(client, handle); if (!valid_handle) { WARN(1, "%s: invalid handle passed to share.\n", __func__); - mutex_unlock(&client->lock); + if (lock_client) + mutex_unlock(&client->lock); return ERR_PTR(-EINVAL); } buffer = handle->buffer; ion_buffer_get(buffer); - mutex_unlock(&client->lock); + if (lock_client) + mutex_unlock(&client->lock); exp_info.ops = &dma_buf_ops; exp_info.size = buffer->size; @@ -1170,14 +1162,21 @@ struct dma_buf *ion_share_dma_buf(struct return dmabuf; } + +struct dma_buf *ion_share_dma_buf(struct ion_client *client, + struct ion_handle *handle) +{ + return __ion_share_dma_buf(client, handle, true); +} EXPORT_SYMBOL(ion_share_dma_buf); -int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle) +static int __ion_share_dma_buf_fd(struct ion_client *client, + struct ion_handle *handle, bool lock_client) { struct dma_buf *dmabuf; int fd; - dmabuf = ion_share_dma_buf(client, handle); + dmabuf = __ion_share_dma_buf(client, handle, lock_client); if (IS_ERR(dmabuf)) return PTR_ERR(dmabuf); @@ -1187,8 +1186,19 @@ int ion_share_dma_buf_fd(struct ion_clie return fd; } + +int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle) +{ + return __ion_share_dma_buf_fd(client, handle, true); +} EXPORT_SYMBOL(ion_share_dma_buf_fd); +static int ion_share_dma_buf_fd_nolock(struct ion_client *client, + struct ion_handle *handle) +{ + return __ion_share_dma_buf_fd(client, handle, false); +} + struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd) { struct dma_buf *dmabuf; @@ -1335,11 +1345,15 @@ static long ion_ioctl(struct file *filp, { struct ion_handle *handle; - handle = ion_handle_get_by_id(client, data.handle.handle); - if (IS_ERR(handle)) + mutex_lock(&client->lock); + handle = ion_handle_get_by_id_nolock(client, data.handle.handle); + if (IS_ERR(handle)) { + mutex_unlock(&client->lock); return PTR_ERR(handle); - data.fd.fd = ion_share_dma_buf_fd(client, handle); - ion_handle_put(handle); + } + data.fd.fd = ion_share_dma_buf_fd_nolock(client, handle); + ion_handle_put_nolock(handle); + mutex_unlock(&client->lock); if (data.fd.fd < 0) ret = data.fd.fd; break;