memcpy should only copy for length of compile time struct

Author: RetiredWizard

shared-module/displayio/__init__.c

@@ -203,8 +203,8 @@ void malloc_display_memory(void) {
     if (max_num_displays > CIRCUITPY_DISPLAY_LIMIT) {
         display_buses = (primary_display_bus_t *)port_malloc(sizeof(primary_display_bus_t) * max_num_displays, false);
         displays = (primary_display_t *)port_malloc(sizeof(primary_display_t) * max_num_displays, false);
-        memcpy(display_buses, &display_busesx[0], sizeof(primary_display_bus_t) * max_num_displays);
-        memcpy(displays, &displaysx[0], sizeof(primary_display_t) * max_num_displays);
+        memcpy(display_buses, &display_busesx[0], sizeof(primary_display_bus_t) * CIRCUITPY_DISPLAY_LIMIT);
+        memcpy(displays, &displaysx[0], sizeof(primary_display_t) * CIRCUITPY_DISPLAY_LIMIT);
     }
     #endif
 }

shared-module/displayio/__init__.h

@@ -99,8 +99,8 @@ typedef struct {
     };
 } primary_display_t;
 
-extern primary_display_bus_t display_busesx[];
-extern primary_display_t displaysx[];
+extern primary_display_bus_t display_busesx[CIRCUITPY_DISPLAY_LIMIT];
+extern primary_display_t displaysx[CIRCUITPY_DISPLAY_LIMIT];
 extern primary_display_bus_t *display_buses;
 extern primary_display_t *displays;
 

supervisor/shared/web_workflow/web_workflow.c

@@ -1567,7 +1567,7 @@ static bool supervisor_filesystem_access_could_block(void) {
     (void)common_hal_os_getenv_int("CIRCUITPY_DISPLAY_LIMIT", &max_num_displays);
     #endif
     // Check displays to see if it's on a fourwire (SPI) bus. If it is, blocking is possible
-    for (size_t i = 0; i < max_num_displays; i++) {
+    for (mp_int_t i = 0; i < max_num_displays; i++) {
         if (display_buses[i].bus_base.type != &fourwire_fourwire_type) {
             continue;
         }