Fix: Large stack allocation in compositor

When COM_EXPORT_GRAPHVIZ is enabled, DebugInfo::graphviz
uses a char[1000000] as local variable. When this function
is called this is allocated on the stack, which has a size
of just 1MB on mac and may cause a stack overflow.

This patch allocates the memory on the heap and frees
the memory at the end of the function.

Reviewed By: LazyDodo

Differential Revision: https://developer.blender.org/D13628

1 files changed, 4 insertions, 2 deletions

diff --git a/source/blender/compositor/intern/COM_Debug.cc b/source/blender/compositor/intern/COM_Debug.cc
index 50a69e55b2b..8525e2fde50 100644
--- a/source/blender/compositor/intern/COM_Debug.cc
+++ b/source/blender/compositor/intern/COM_Debug.cc
@@ -431,8 +431,9 @@ void DebugInfo::graphviz(const ExecutionSystem *system, StringRefNull name)
   if (!COM_EXPORT_GRAPHVIZ) {
     return;
   }
-  char str[1000000];
-  if (graphviz_system(system, str, sizeof(str) - 1)) {
+  const int max_textlength = 1000000;
+  char *str = (char *)MEM_mallocN(max_textlength, __func__);
+  if (graphviz_system(system, str, max_textlength - 1)) {
     char basename[FILE_MAX];
     char filename[FILE_MAX];
 
@@ -451,6 +452,7 @@ void DebugInfo::graphviz(const ExecutionSystem *system, StringRefNull name)
     fputs(str, fp);
     fclose(fp);
   }
+  MEM_freeN(str);
 }
 
 static std::string get_operations_export_dir()