netlink: don't crash if prefix for < byte is requested

If prefix is used with a datatype that has less than 8 bits an
assertion is triggered:

src/netlink.c:243: netlink_gen_raw_data: Assertion `len > 0' failed.

This is esoteric, the alternative would be to restrict prefixes
to ipv4/ipv6 addresses.

Simpler fix is to use round_up instead of divide.

Signed-off-by: Florian Westphal <fw@strlen.de>

1 files changed, 21 insertions, 0 deletions

diff --git a/tests/py/ip/ip.t.json b/tests/py/ip/ip.t.json
index 882c94eb..a170e5c1 100644
--- a/tests/py/ip/ip.t.json
+++ b/tests/py/ip/ip.t.json
@@ -1809,3 +1809,24 @@
         }
     }
 ]
+
+# ip dscp 1/6
+[
+    {
+        "match": {
+            "left": {
+                "&": [
+                    {
+                        "payload": {
+                            "field": "dscp",
+                            "protocol": "ip"
+                        }
+                    },
+                    63
+                ]
+            },
+            "op": "==",
+            "right": "lephb"
+        }
+    }
+]