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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 02FA2C43457 for ; Mon, 12 Oct 2020 14:08:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C28A520776 for ; Mon, 12 Oct 2020 14:08:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602511713; bh=myPPuIP290xrbvnpk6NifaYnCfQgqD8J2edymKs38XM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=VxHVz7yPyrmJNMwcLodNNwI+Tmu7at0O+ZDNlH4phSF3yY30zpedb8khkWfmhbfbo AueeRE3JWuZ+/zwNl09ykCNCmYBPvSORlxnD+AQt7g8fiXk52hjmnkmQiQCuFmZv+5 m+2DCERFSi3x5D0otrZLZwmroMkEBfjjb0zMB4gs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731488AbgJLOIc (ORCPT ); Mon, 12 Oct 2020 10:08:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:35654 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730584AbgJLNda (ORCPT ); Mon, 12 Oct 2020 09:33:30 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 5B2002074F; Mon, 12 Oct 2020 13:33:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602509609; bh=myPPuIP290xrbvnpk6NifaYnCfQgqD8J2edymKs38XM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=A+UN8RCVAXPEA9D/GGVIBiQjBhlVixSgiIPWbI0SkRKhc/+rSOFFRSxAEtLUYBFnr 7HPtPb97JSuMLaKtGoMmUAftLzxY4VC55tdQXMVtWlydjyvjlACvnobLuPth2FZxjC bL/fETqPuQQRv7Y2UMcjlESUVKHpA6YBule/1mWA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stefano Garzarella , "David S. Miller" , Sasha Levin Subject: [PATCH 4.9 01/54] vsock/virtio: use RCU to avoid use-after-free on the_virtio_vsock Date: Mon, 12 Oct 2020 15:26:23 +0200 Message-Id: <20201012132629.662022259@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201012132629.585664421@linuxfoundation.org> References: <20201012132629.585664421@linuxfoundation.org> User-Agent: quilt/0.66 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Stefano Garzarella [ Upstream commit 9c7a5582f5d720dc35cfcc42ccaded69f0642e4a ] Some callbacks used by the upper layers can run while we are in the .remove(). A potential use-after-free can happen, because we free the_virtio_vsock without knowing if the callbacks are over or not. To solve this issue we move the assignment of the_virtio_vsock at the end of .probe(), when we finished all the initialization, and at the beginning of .remove(), before to release resources. For the same reason, we do the same also for the vdev->priv. We use RCU to be sure that all callbacks that use the_virtio_vsock ended before freeing it. This is not required for callbacks that use vdev->priv, because after the vdev->config->del_vqs() we are sure that they are ended and will no longer be invoked. We also take the mutex during the .remove() to avoid that .probe() can run while we are resetting the device. Signed-off-by: Stefano Garzarella Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/vmw_vsock/virtio_transport.c | 50 ++++++++++++++++++++------------ 1 file changed, 32 insertions(+), 18 deletions(-) diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c index 0bd5a60f3bdeb..32ad7cfa5fa74 100644 --- a/net/vmw_vsock/virtio_transport.c +++ b/net/vmw_vsock/virtio_transport.c @@ -62,19 +62,22 @@ struct virtio_vsock { u32 guest_cid; }; -static struct virtio_vsock *virtio_vsock_get(void) -{ - return the_virtio_vsock; -} - static u32 virtio_transport_get_local_cid(void) { - struct virtio_vsock *vsock = virtio_vsock_get(); + struct virtio_vsock *vsock; + u32 ret; - if (!vsock) - return VMADDR_CID_ANY; + rcu_read_lock(); + vsock = rcu_dereference(the_virtio_vsock); + if (!vsock) { + ret = VMADDR_CID_ANY; + goto out_rcu; + } - return vsock->guest_cid; + ret = vsock->guest_cid; +out_rcu: + rcu_read_unlock(); + return ret; } static void @@ -156,10 +159,12 @@ virtio_transport_send_pkt(struct virtio_vsock_pkt *pkt) struct virtio_vsock *vsock; int len = pkt->len; - vsock = virtio_vsock_get(); + rcu_read_lock(); + vsock = rcu_dereference(the_virtio_vsock); if (!vsock) { virtio_transport_free_pkt(pkt); - return -ENODEV; + len = -ENODEV; + goto out_rcu; } if (pkt->reply) @@ -170,6 +175,9 @@ virtio_transport_send_pkt(struct virtio_vsock_pkt *pkt) spin_unlock_bh(&vsock->send_pkt_list_lock); queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work); + +out_rcu: + rcu_read_unlock(); return len; } @@ -478,7 +486,8 @@ static int virtio_vsock_probe(struct virtio_device *vdev) return ret; /* Only one virtio-vsock device per guest is supported */ - if (the_virtio_vsock) { + if (rcu_dereference_protected(the_virtio_vsock, + lockdep_is_held(&the_virtio_vsock_mutex))) { ret = -EBUSY; goto out; } @@ -502,8 +511,6 @@ static int virtio_vsock_probe(struct virtio_device *vdev) vsock->rx_buf_max_nr = 0; atomic_set(&vsock->queued_replies, 0); - vdev->priv = vsock; - the_virtio_vsock = vsock; mutex_init(&vsock->tx_lock); mutex_init(&vsock->rx_lock); mutex_init(&vsock->event_lock); @@ -522,6 +529,9 @@ static int virtio_vsock_probe(struct virtio_device *vdev) virtio_vsock_event_fill(vsock); mutex_unlock(&vsock->event_lock); + vdev->priv = vsock; + rcu_assign_pointer(the_virtio_vsock, vsock); + mutex_unlock(&the_virtio_vsock_mutex); return 0; @@ -536,6 +546,12 @@ static void virtio_vsock_remove(struct virtio_device *vdev) struct virtio_vsock *vsock = vdev->priv; struct virtio_vsock_pkt *pkt; + mutex_lock(&the_virtio_vsock_mutex); + + vdev->priv = NULL; + rcu_assign_pointer(the_virtio_vsock, NULL); + synchronize_rcu(); + flush_work(&vsock->rx_work); flush_work(&vsock->tx_work); flush_work(&vsock->event_work); @@ -565,12 +581,10 @@ static void virtio_vsock_remove(struct virtio_device *vdev) } spin_unlock_bh(&vsock->send_pkt_list_lock); - mutex_lock(&the_virtio_vsock_mutex); - the_virtio_vsock = NULL; - mutex_unlock(&the_virtio_vsock_mutex); - vdev->config->del_vqs(vdev); + mutex_unlock(&the_virtio_vsock_mutex); + kfree(vsock); } -- 2.25.1