bond: Support null argument to bond_ref().

This is consistent with the other ref functions, and was causing
segmentation faults in some test cases.

Reported-by: Mukesh Hira <mhira@nicira.com>
Signed-off-by: Ethan Jackson <ethan@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/bond.c b/lib/bond.c
index 183c37be..b3ae0c4b 100644
--- a/lib/bond.c
+++ b/lib/bond.c
@@ -195,8 +195,10 @@ bond_ref(const struct bond *bond_)
 {
     struct bond *bond = CONST_CAST(struct bond *, bond_);
 
-    ovs_assert(bond->ref_cnt > 0);
-    bond->ref_cnt++;
+    if (bond) {
+        ovs_assert(bond->ref_cnt > 0);
+        bond->ref_cnt++;
+    }
     return bond;
 }