From patchwork Tue Jan 5 14:36:39 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Charan Teja Kalla X-Patchwork-Id: 11999159 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=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 AD5F9C433E0 for ; Tue, 5 Jan 2021 14:37:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8570D22B49 for ; Tue, 5 Jan 2021 14:37:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726864AbhAEOhv (ORCPT ); Tue, 5 Jan 2021 09:37:51 -0500 Received: from m43-15.mailgun.net ([69.72.43.15]:47284 "EHLO m43-15.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726618AbhAEOhu (ORCPT ); Tue, 5 Jan 2021 09:37:50 -0500 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1609857445; h=Content-Transfer-Encoding: Content-Type: MIME-Version: Message-Id: Date: Subject: Cc: To: From: Sender; bh=4DiNJfGzzRCDF2FL02HtG0SOdr7LDb46DzlmbUJfV6s=; b=X45A930qsyotc7/AD+4OMqx7f3foVhfJ7jUfObJQTt8ghcmLls1hQ4Mvgq58UmK+qXqvyUBt Aq4WBL9vEYpQD9iXanVarK1oExM2NmjDs7zLV6WSUX54dDTWCV98XCEpQxZZzgsTEPj/Ml7v JVDstBAXK/rtN2L16vX18hvQ/M8= X-Mailgun-Sending-Ip: 69.72.43.15 X-Mailgun-Sid: WyI3ZjU0NiIsICJsaW51eC1tZWRpYUB2Z2VyLmtlcm5lbC5vcmciLCAiYmU5ZTRhIl0= Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n08.prod.us-west-2.postgun.com with SMTP id 5ff47988b73be0303d2da1d0 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Tue, 05 Jan 2021 14:36:56 GMT Sender: charante=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id AF37CC433C6; Tue, 5 Jan 2021 14:36:56 +0000 (UTC) Received: from charante-linux.qualcomm.com (unknown [202.46.22.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: charante) by smtp.codeaurora.org (Postfix) with ESMTPSA id E3526C433CA; Tue, 5 Jan 2021 14:36:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org E3526C433CA Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=charante@codeaurora.org From: Charan Teja Reddy To: sumit.semwal@linaro.org, christian.koenig@amd.com, arnd@arndb.de Cc: linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, Charan Teja Reddy , "# 5 . 4+" Subject: [PATCH V2] dmabuf: fix use-after-free of dmabuf's file->f_inode Date: Tue, 5 Jan 2021 20:06:39 +0530 Message-Id: <1609857399-31549-1-git-send-email-charante@codeaurora.org> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org It is observed 'use-after-free' on the dmabuf's file->f_inode with the race between closing the dmabuf file and reading the dmabuf's debug info. Consider the below scenario where P1 is closing the dma_buf file and P2 is reading the dma_buf's debug info in the system: P1 P2 dma_buf_debug_show() dma_buf_put() __fput() file->f_op->release() dput() .... dentry_unlink_inode() iput(dentry->d_inode) (where the inode is freed) mutex_lock(&db_list.lock) read 'dma_buf->file->f_inode' (the same inode is freed by P1) mutex_unlock(&db_list.lock) dentry->d_op->d_release()--> dma_buf_release() ..... mutex_lock(&db_list.lock) removes the dmabuf from the list mutex_unlock(&db_list.lock) In the above scenario, when dma_buf_put() is called on a dma_buf, it first frees the dma_buf's file->f_inode(=dentry->d_inode) and then removes this dma_buf from the system db_list. In between P2 traversing the db_list tries to access this dma_buf's file->f_inode that was freed by P1 which is a use-after-free case. Since, __fput() calls f_op->release first and then later calls the d_op->d_release, move the dma_buf's db_list removal from d_release() to f_op->release(). This ensures that dma_buf's file->f_inode is not accessed after it is released. Cc: # 5.4+ Fixes: 4ab59c3c638c ("dma-buf: Move dma_buf_release() from fops to dentry_ops") Acked-by: Christian König Signed-off-by: Charan Teja Reddy --- V2: Resending with stable tags and Acks V1: https://lore.kernel.org/patchwork/patch/1360118/ drivers/dma-buf/dma-buf.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 0eb80c1..a14dcbb 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -76,10 +76,6 @@ static void dma_buf_release(struct dentry *dentry) dmabuf->ops->release(dmabuf); - mutex_lock(&db_list.lock); - list_del(&dmabuf->list_node); - mutex_unlock(&db_list.lock); - if (dmabuf->resv == (struct dma_resv *)&dmabuf[1]) dma_resv_fini(dmabuf->resv); @@ -88,6 +84,22 @@ static void dma_buf_release(struct dentry *dentry) kfree(dmabuf); } +static int dma_buf_file_release(struct inode *inode, struct file *file) +{ + struct dma_buf *dmabuf; + + if (!is_dma_buf_file(file)) + return -EINVAL; + + dmabuf = file->private_data; + + mutex_lock(&db_list.lock); + list_del(&dmabuf->list_node); + mutex_unlock(&db_list.lock); + + return 0; +} + static const struct dentry_operations dma_buf_dentry_ops = { .d_dname = dmabuffs_dname, .d_release = dma_buf_release, @@ -413,6 +425,7 @@ static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file) } static const struct file_operations dma_buf_fops = { + .release = dma_buf_file_release, .mmap = dma_buf_mmap_internal, .llseek = dma_buf_llseek, .poll = dma_buf_poll,