netdev - Re: [PATCH net] vhost: synchronize IOTLB message with dev cleanup

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Message-Id: <20180524.153519.452683890193996505.davem@davemloft.net>
Date:   Thu, 24 May 2018 15:35:19 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     jasowang@...hat.com
Cc:     mst@...hat.com, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] vhost: synchronize IOTLB message with dev cleanup

From: Jason Wang <jasowang@...hat.com>
Date: Tue, 22 May 2018 19:58:57 +0800

> DaeRyong Jeong reports a race between vhost_dev_cleanup() and
> vhost_process_iotlb_msg():
> 
> Thread interleaving:
> CPU0 (vhost_process_iotlb_msg)			CPU1 (vhost_dev_cleanup)
> (In the case of both VHOST_IOTLB_UPDATE and
> VHOST_IOTLB_INVALIDATE)
> =====						=====
> 						vhost_umem_clean(dev->iotlb);
> if (!dev->iotlb) {
> 	        ret = -EFAULT;
> 		        break;
> }
> 						dev->iotlb = NULL;
> 
> The reason is we don't synchronize between them, fixing by protecting
> vhost_process_iotlb_msg() with dev mutex.
> 
> Reported-by: DaeRyong Jeong <threeearcat@...il.com>
> Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API")
> Signed-off-by: Jason Wang <jasowang@...hat.com>

Michael, please review.