net/virtio-user: check FD flags getting failure

[ upstream commit 6abf10a ]

The function fcntl() could return errors,
the return value need to be checked.

Fixes: 6a84c37 ("net/virtio-user: add vhost-user adapter layer")

Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>

drivers/net/virtio/virtio_user/vhost_user.c

@@ -468,8 +468,10 @@ vhost_user_setup(struct virtio_user_dev *dev)
 	}
 
 	flag = fcntl(fd, F_GETFD);
-	if (fcntl(fd, F_SETFD, flag | FD_CLOEXEC) < 0)
-		PMD_DRV_LOG(WARNING, "fcntl failed, %s", strerror(errno));
+	if (flag == -1)
+		PMD_DRV_LOG(WARNING, "fcntl get fd failed, %s", strerror(errno));
+	else if (fcntl(fd, F_SETFD, flag | FD_CLOEXEC) < 0)
+		PMD_DRV_LOG(WARNING, "fcntl set fd failed, %s", strerror(errno));
 
 	memset(&un, 0, sizeof(un));
 	un.sun_family = AF_UNIX;