dpif-linux: Avoid segfault on netdev_get_stats() without kernel module.

netdev_linux_get_stats() calls into netdev_vport_get_stats(), which in
turn attempts a transaction on genl_sock.  If the kernel module isn't
loaded, then genl_sock won't be there, and in any case there's nothing that
guarantees that it's been initialized yet.

This fixes the problem by ensuring that dpif_linux was initialized properly
before attempting a transaction on genl_sock.

Reported-by: Aaron Rosen <arosen@clemson.edu>

1 files changed, 9 insertions, 0 deletions

diff --git a/lib/dpif-linux.c b/lib/dpif-linux.c
index 75cff0c4..fd08e640 100644
--- a/lib/dpif-linux.c
+++ b/lib/dpif-linux.c
@@ -1254,6 +1254,15 @@ dpif_linux_vport_transact(const struct dpif_linux_vport *request,
 
     assert((reply != NULL) == (bufp != NULL));
 
+    error = dpif_linux_init();
+    if (error) {
+        if (reply) {
+            *bufp = NULL;
+            dpif_linux_vport_init(reply);
+        }
+        return error;
+    }
+
     request_buf = ofpbuf_new(1024);
     dpif_linux_vport_to_ofpbuf(request, request_buf);
     error = nl_sock_transact(genl_sock, request_buf, bufp);