From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:35300 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753676AbeFIPcw (ORCPT ); Sat, 9 Jun 2018 11:32:52 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, DaeRyong Jeong , Jason Wang , "Michael S. Tsirkin" , "David S. Miller" Subject: [PATCH 4.16 31/48] vhost: synchronize IOTLB message with dev cleanup Date: Sat, 9 Jun 2018 17:29:43 +0200 Message-Id: <20180609145949.801562840@linuxfoundation.org> In-Reply-To: <20180609145947.679103414@linuxfoundation.org> References: <20180609145947.679103414@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jason Wang [ Upstream commit 1b15ad683ab42a203f98b67045b40720e99d0e9a ] 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 Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API") Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/vhost/vhost.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -981,6 +981,7 @@ static int vhost_process_iotlb_msg(struc { int ret = 0; + mutex_lock(&dev->mutex); vhost_dev_lock_vqs(dev); switch (msg->type) { case VHOST_IOTLB_UPDATE: @@ -1016,6 +1017,8 @@ static int vhost_process_iotlb_msg(struc } vhost_dev_unlock_vqs(dev); + mutex_unlock(&dev->mutex); + return ret; } ssize_t vhost_chr_write_iter(struct vhost_dev *dev,