From: Matthew Fernandez <matthew.fernandez@gmail.com>
Date: Sat, 14 Nov 2020 19:44:21 +0000 (-0800)
Subject: anticipate find_tight_subtree() returning NULL
X-Git-Tag: 2.46.1~31^2~14
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=7108742ef4c868d453a0d056ef417c5c5c9e3a12;p=graphviz

anticipate find_tight_subtree() returning NULL

Related to #1801.
---

diff --git a/lib/common/ns.c b/lib/common/ns.c
index e1b0e2859..e47ec6616 100644
--- a/lib/common/ns.c
+++ b/lib/common/ns.c
@@ -493,7 +493,7 @@ int feasible_tree(void)
   Agedge_t *ee;
   subtree_t **tree, *tree0, *tree1;
   int i, subtree_count = 0;
-  STheap_t *heap;
+  STheap_t *heap = NULL;
   int error = 0;
 
   /* initialization */
@@ -506,6 +506,10 @@ int feasible_tree(void)
   for (n = GD_nlist(G); n; n = ND_next(n)) {
         if (ND_subtree(n) == 0) {
                 tree[subtree_count] = find_tight_subtree(n);
+                if (tree[subtree_count] == NULL) {
+                    error = 2;
+                    goto end;
+                }
                 subtree_count++;
         }
   }
@@ -522,10 +526,11 @@ int feasible_tree(void)
     STheapify(heap,tree1->heap_index);
   }
 
+end:
   free(heap);
   for (i = 0; i < subtree_count; i++) free(tree[i]);
   free(tree);
-  if (error) return 1;
+  if (error) return error;
   assert(Tree_edge.size == N_nodes - 1);
   init_cutvalues();
   return 0;