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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 A0A99C433E6 for ; Mon, 11 Jan 2021 13:22:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7629121BE5 for ; Mon, 11 Jan 2021 13:22:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730412AbhAKNWI (ORCPT ); Mon, 11 Jan 2021 08:22:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:36510 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733179AbhAKNSq (ORCPT ); Mon, 11 Jan 2021 08:18:46 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2BD06229C4; Mon, 11 Jan 2021 13:18:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610371110; bh=Z9cMea0DCwPV9ekGawv44LwH2gcwZ+Yd/UNJSXtQM6w=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=x+TMZy7a1LUA5Jw96ImhZ1fta3An/1dK8DptBXMV1kNHHBihFgAdQq/kFc8rT8xnh tuQpkXxlsZWd9rEmkOxu4DExNDwRV2XQuK2qEn/sGVM9znX2/rS3EqhYSIo4YcuDNW pZgFnBwLp40fXrGneVltH5AqpxUK5ZYfNFQ7S4E0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Christian=20K=C3=B6nig?= , Charan Teja Reddy , Sumit Semwal , Thomas Zimmermann Subject: [PATCH 5.10 128/145] dmabuf: fix use-after-free of dmabufs file->f_inode Date: Mon, 11 Jan 2021 14:02:32 +0100 Message-Id: <20210111130054.664526024@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210111130048.499958175@linuxfoundation.org> References: <20210111130048.499958175@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Charan Teja Reddy commit 05cd84691eafcd7959a1e120d5e72c0dd98c5d91 upstream. 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.x- Fixes: 4ab59c3c638c ("dma-buf: Move dma_buf_release() from fops to dentry_ops") Acked-by: Christian König Signed-off-by: Charan Teja Reddy Signed-off-by: Sumit Semwal Signed-off-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/1609857399-31549-1-git-send-email-charante@codeaurora.org Signed-off-by: Greg Kroah-Hartman --- drivers/dma-buf/dma-buf.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-) --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -76,10 +76,6 @@ static void dma_buf_release(struct dentr 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 dentr 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 s } 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,