wmem: permit lookups in NULL trees (oops)

Change-Id: I222b95b48b7ac8debbd717b32dd471742222c16b
Reviewed-on: https://code.wireshark.org/review/9177
Reviewed-by: Evan Huus <eapache@gmail.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/epan/wmem/wmem_tree.c b/epan/wmem/wmem_tree.c
index ef0ea72fb9..1db2923a31 100644
--- a/epan/wmem/wmem_tree.c
+++ b/epan/wmem/wmem_tree.c
@@ -369,7 +369,13 @@ lookup_or_insert32(wmem_tree_t *tree, guint32 key,
 static void *
 wmem_tree_lookup(wmem_tree_t *tree, const void *key, compare_func cmp)
 {
-    wmem_tree_node_t *node = tree->root;
+    wmem_tree_node_t *node;
+
+    if (tree == NULL || key == NULL) {
+        return NULL;
+    }
+
+    node = tree->root;
 
     while (node) {
         int result = cmp(key, node->key);