util-radix-tree: fix memleak

Logic used when adding a new prefix to a node was not correct
as we were allocating a prefix that could be at the end unused.
This patch is updating the code to have a complete creation to
be done if and only if we are needing the complete object. In
the other cases, it was enough to use the function input values.

This fixes:

104 (48 direct, 56 indirect) bytes in 2 blocks are definitely lost in loss record 184 of 327
   at 0x4C29C0F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
   by 0x9C2DAD: SCRadixCreatePrefix (util-radix-tree.c:144)
   by 0x9AFA5B: SCRadixAddKey (util-radix-tree.c:522)
   by 0x9B1A4D: SCRadixAddKeyIPV4Netblock (util-radix-tree.c:897)
   by 0x67C824: IPOnlyPrepare (detect-engine-iponly.c:1197)
   by 0x55172B: SigAddressPrepareStage2 (detect.c:3534)
   by 0x5486F4: SigGroupBuild (detect.c:4671)
   by 0x547C87: SigLoadSignatures (detect.c:538)
   by 0x8FB5D0: LoadSignatures (suricata.c:1976)
   by 0x8F3B32: main (suricata.c:2342)

src/util-radix-tree.c

@@ -496,9 +496,6 @@ static SCRadixNode *SCRadixAddKey(uint8_t *key_stream, uint16_t key_bitlen,
     SCRadixNode *parent = NULL;
     SCRadixNode *inter_node = NULL;
     SCRadixNode *bottom_node = NULL;
-
-    SCRadixPrefix *prefix = NULL;
-
     void *ptmp;
 
     uint8_t *stream = NULL;
@@ -519,14 +516,14 @@ static SCRadixNode *SCRadixAddKey(uint8_t *key_stream, uint16_t key_bitlen,
     /* chop the ip address against a netmask */
     MaskIPNetblock(key_stream, netmask, key_bitlen);
 
-    if ( (prefix = SCRadixCreatePrefix(key_stream, key_bitlen, user,
-                                       netmask)) == NULL) {
-        SCLogError(SC_ERR_RADIX_TREE_GENERIC, "Error creating prefix");
-        return NULL;
-    }
-
     /* the very first element in the radix tree */
     if (tree->head == NULL) {
+        SCRadixPrefix *prefix = NULL;
+        if ( (prefix = SCRadixCreatePrefix(key_stream, key_bitlen, user,
+                        netmask)) == NULL) {
+            SCLogError(SC_ERR_RADIX_TREE_GENERIC, "Error creating prefix");
+            return NULL;
+        }
         node = SCRadixCreateNode();
         if (node == NULL)
             return NULL;
@@ -558,8 +555,8 @@ static SCRadixNode *SCRadixAddKey(uint8_t *key_stream, uint16_t key_bitlen,
     }
 
     node = tree->head;
-    stream = prefix->stream;
-    bitlen = prefix->bitlen;
+    stream = key_stream;
+    bitlen = key_bitlen;
 
     /* we walk down the tree only when we satisfy 2 conditions.  The first one
      * being the incoming prefix is shorter than the differ bit of the current
@@ -695,13 +692,19 @@ static SCRadixNode *SCRadixAddKey(uint8_t *key_stream, uint16_t key_bitlen,
                 }
             }
         } else {
-            node->prefix = SCRadixCreatePrefix(prefix->stream, prefix->bitlen,
+            node->prefix = SCRadixCreatePrefix(key_stream, key_bitlen,
                                                user, 255);
         }
         return node;
     }
 
     /* create the leaf node for the new key */
+    SCRadixPrefix *prefix = NULL;
+    if ( (prefix = SCRadixCreatePrefix(key_stream, key_bitlen, user,
+                    netmask)) == NULL) {
+        SCLogError(SC_ERR_RADIX_TREE_GENERIC, "Error creating prefix");
+        return NULL;
+    }
     new_node = SCRadixCreateNode();
     new_node->prefix = prefix;
     new_node->bit = prefix->bitlen;