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=-6.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 23E85C677FC for ; Thu, 11 Oct 2018 15:40:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D3E1021477 for ; Thu, 11 Oct 2018 15:40:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="nYj1Imm/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D3E1021477 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 S1730271AbeJKXI1 (ORCPT ); Thu, 11 Oct 2018 19:08:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:38758 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726647AbeJKXI0 (ORCPT ); Thu, 11 Oct 2018 19:08:26 -0400 Received: from localhost (ip-213-127-77-176.ip.prioritytelecom.net [213.127.77.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1BF542098A; Thu, 11 Oct 2018 15:40:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1539272442; bh=Ejzu0teA2upWqMRyq3cRB6tcg6K4iVBHno+1uFgjzcs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nYj1Imm/NEt2o9vakHFrH42rR9pdHZP+LkcoEj0nJj+7ubJGr37hFzVD1KCwzv/24 n/AZD8+6tiJk/69QMNygYbCkYodB7atrK3wtLbvb13JhrfPrGCNePAWuTNwboK5kJV yxZYPalSEGDmi9Tc43G05lSMoqYZKxs8bThmtNck= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Greg Hackmann , Laura Abbott Subject: [PATCH 3.18 062/120] staging: android: ion: fix ION_IOC_{MAP,SHARE} use-after-free Date: Thu, 11 Oct 2018 17:34:03 +0200 Message-Id: <20181011152552.338424664@linuxfoundation.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181011152549.500488630@linuxfoundation.org> References: <20181011152549.500488630@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 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Greg Hackmann commit 2c155709e4ef2d86d0176aac82e44c048a7e0255 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- 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 @@ -451,18 +451,6 @@ 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) { @@ -1138,23 +1126,27 @@ 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) { 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); dmabuf = dma_buf_export(buffer, &dma_buf_ops, buffer->size, O_RDWR, NULL); @@ -1165,14 +1157,21 @@ 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); @@ -1182,8 +1181,19 @@ 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; @@ -1330,11 +1340,15 @@ 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;