[dpdk-stable] [PATCH v19.11 6/6] vhost: fix potential fd leak

[Ferruh Yigit]

From: Xuan Ding <xuan.ding at intel.com>

Vhost will create temporary file when receiving VHOST_USER_GET_INFLIGHT_FD
message. Malicious guest can send endless this message to drain out the
resource of host.

When receiving VHOST_USER_GET_INFLIGHT_FD message repeatedly, closing the
file created during the last handling of this message.

Fixes: d87f1a1cb7b666550 ("vhost: support inflight info sharing")
Cc: stable at dpdk.org

This issue has been assigned CVE-2020-10726

Signed-off-by: Xuan Ding <xuan.ding at intel.com>
Signed-off-by: Xiaolong Ye <xiaolong.ye at intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>
---
 lib/librte_vhost/vhost_user.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 2a4ba205cf..8954f7930e 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -206,7 +206,7 @@ vhost_backend_cleanup(struct virtio_net *dev)
 			dev->inflight_info->addr = NULL;
 		}
 
-		if (dev->inflight_info->fd > 0) {
+		if (dev->inflight_info->fd >= 0) {
 			close(dev->inflight_info->fd);
 			dev->inflight_info->fd = -1;
 		}
@@ -1408,6 +1408,7 @@ vhost_user_get_inflight_fd(struct virtio_net **pdev,
 				"failed to alloc dev inflight area\n");
 			return RTE_VHOST_MSG_RESULT_ERR;
 		}
+		dev->inflight_info->fd = -1;
 	}
 
 	num_queues = msg->payload.inflight.num_queues;
@@ -1438,6 +1439,11 @@ vhost_user_get_inflight_fd(struct virtio_net **pdev,
 		dev->inflight_info->addr = NULL;
 	}
 
+	if (dev->inflight_info->fd >= 0) {
+		close(dev->inflight_info->fd);
+		dev->inflight_info->fd = -1;
+	}
+
 	dev->inflight_info->addr = addr;
 	dev->inflight_info->size = msg->payload.inflight.mmap_size = mmap_size;
 	dev->inflight_info->fd = msg->fds[0] = fd;
@@ -1520,6 +1526,7 @@ vhost_user_set_inflight_fd(struct virtio_net **pdev, VhostUserMsg *msg,
 				"failed to alloc dev inflight area\n");
 			return RTE_VHOST_MSG_RESULT_ERR;
 		}
+		dev->inflight_info->fd = -1;
 	}
 
 	if (dev->inflight_info->addr) {
@@ -1534,8 +1541,10 @@ vhost_user_set_inflight_fd(struct virtio_net **pdev, VhostUserMsg *msg,
 		return RTE_VHOST_MSG_RESULT_ERR;
 	}
 
-	if (dev->inflight_info->fd)
+	if (dev->inflight_info->fd >= 0) {
 		close(dev->inflight_info->fd);
+		dev->inflight_info->fd = -1;
+	}
 
 	dev->inflight_info->fd = fd;
 	dev->inflight_info->addr = addr;
-- 
2.25.2