VPP-189 - Coverity OVERRUN error in port-range

[vpp.git] / vnet / vnet / ip / ip4_mtrie.c

diff --git a/vnet/vnet/ip/ip4_mtrie.c b/vnet/vnet/ip/ip4_mtrie.c
index 461cd64..006610a 100644 (file)
--- a/vnet/vnet/ip/ip4_mtrie.c
+++ b/vnet/vnet/ip/ip4_mtrie.c
@@ -303,7 +303,7 @@ unset_leaf (ip4_fib_mtrie_t * m,
 {
   ip4_fib_mtrie_leaf_t old_leaf, del_leaf;
   i32 n_dst_bits_next_plies;
-  uword i, n_dst_bits_this_ply, old_leaf_is_terminal;
+  i32 i, n_dst_bits_this_ply, old_leaf_is_terminal;
   u8 dst_byte;
 
   ASSERT (a->dst_address_length > 0 && a->dst_address_length <= 32);
@@ -436,10 +436,26 @@ maybe_remap_leaf (ip_lookup_main_t * lm, ip4_fib_mtrie_leaf_t * p)
       if (m)
        {
          was_remapped_to_empty_leaf = m == ~0;
+
+          /*
+           * The intent of the original form - which dates to 2013 or
+           * earlier - is not obvious. Here's the original:
+           * 
+           * if (was_remapped_to_empty_leaf)
+           *   p[0] = (was_remapped_to_empty_leaf
+           *           ? IP4_FIB_MTRIE_LEAF_EMPTY
+           *           : ip4_fib_mtrie_leaf_set_adj_index (m - 1));
+           *
+           * Notice the outer "if (was_remapped_to_empty_leaf)"
+           * means that p[0] is always set to IP4_FIB_MTRIE_LEAF_EMPTY,
+           * and is otherwise left intact.
+           * 
+           * It seems unlikely that the adjacency mapping scheme
+           * works in detail. Coverity correctly complains that the 
+           * else-case of the original ternary expression is dead code.
+           */
          if (was_remapped_to_empty_leaf)
-           p[0] = (was_remapped_to_empty_leaf
-                   ? IP4_FIB_MTRIE_LEAF_EMPTY
-                   : ip4_fib_mtrie_leaf_set_adj_index (m - 1));
+            p[0] = IP4_FIB_MTRIE_LEAF_EMPTY;
        }
     }
   return was_remapped_to_empty_leaf;