Re: [PATCH net-next 2/3] mpls: consistently use u8 to store number of labels

On 8/12/15, 12:17 PM, Robert Shearman wrote:

On 11/08/15 22:45, Roopa Prabhu wrote:

quoted

From: Roopa Prabhu <redacted>

change all types representing number of labels to u8
to be consistent.

This also changes labels to u8 in the light weight
mpls_tunnel_encap structure. This is because the
light weight mpls iptunnel code shares some of the label
encoding functions like nla_get/put_labels with the af_mpls
code.

Signed-off-by: Roopa Prabhu <redacted>
---

...

quoted

@@ -243,11 +243,11 @@ static const struct nla_policy 

rtm_mpls_policy[RTA_MAX+1] = {
  struct mpls_route_config {
      u32            rc_protocol;
      u32            rc_ifindex;
-    u16            rc_via_table;
-    u16            rc_via_alen;
+    u8            rc_via_table;
+    u8            rc_via_alen;

IMHO, it would be better to make rc_via_alen an int to avoid overflow 
which could cause false negatives in this check on the RTA_VIA attribute:

            if (cfg->rc_via_alen > MAX_VIA_ALEN)
                goto errout;

ok,

...

quoted

      u8            rc_via[MAX_VIA_ALEN];
+    u8            rc_output_labels;
      u32            rc_label;
-    u32            rc_output_labels;
      u32            rc_output_label[MAX_NEW_LABELS];
      u32            rc_nlflags;
      enum mpls_payload_type    rc_payload_type;

@@ -751,7 +751,7 @@ int nla_put_labels(struct sk_buff *skb, int 

attrtype,
  EXPORT_SYMBOL_GPL(nla_put_labels);

  int nla_get_labels(const struct nlattr *nla,
-           u32 max_labels, u32 *labels, u32 label[])
+           u32 max_labels, u8 *labels, u32 label[])

How about making max_labels a u8? That would make it even more 
consistent and avoids any problem of overflow in the number of labels.

yes, I did want to change max_labels to u8. will do in v2.

thanks,
Roopa