2 files changed, 22 insertions, 0 deletions
diff --git a/supervisor/shared/stack.c b/supervisor/shared/stack.c
index 6b74742eb..8f4da4ce6 100755
--- a/supervisor/shared/stack.c
+++ b/supervisor/shared/stack.c
@@ -27,6 +27,7 @@
 #include "stack.h"
 
 #include "py/mpconfig.h"
+#include "py/runtime.h"
 #include "supervisor/cpu.h"
 
 extern uint32_t _estack;
@@ -37,6 +38,8 @@ supervisor_allocation* stack_alloc = NULL;
 
 #define EXCEPTION_STACK_SIZE 1024
 
+#define STACK_CANARY_VALUE 0x017829ef
+
 void allocate_stack(void) {
     mp_uint_t regs[10];
     mp_uint_t sp = cpu_get_regs_and_sp(regs);
@@ -50,6 +53,19 @@ void allocate_stack(void) {
     } else {
         current_stack_size = next_stack_size;
     }
+    *stack_alloc->ptr = STACK_CANARY_VALUE;
+}
+
+inline bool stack_ok(void) {
+    return *stack_alloc->ptr == STACK_CANARY_VALUE;
+}
+
+inline void assert_heap_ok(void) {
+    if (!stack_ok()) {
+        asm("nop");
+        while(true) {}
+        mp_raise_RuntimeError(translate("Stack clobbered heap."));
+    }
 }
 
 void stack_init(void) {
@@ -58,6 +74,7 @@ void stack_init(void) {
 
 void stack_resize(void) {
     if (next_stack_size == current_stack_size) {
+        *stack_alloc->ptr = STACK_CANARY_VALUE;
         return;
     }
     free_memory(stack_alloc);
diff --git a/supervisor/shared/stack.h b/supervisor/shared/stack.h
index 3a5c18e7d..8f1e881f2 100755
--- a/supervisor/shared/stack.h
+++ b/supervisor/shared/stack.h
@@ -37,5 +37,10 @@ void stack_init(void);
 void stack_resize(void);
 void set_next_stack_size(uint32_t size);
 uint32_t get_current_stack_size(void);
+bool stack_ok(void);
+
+// Use this after any calls into a library which may use a lot of stack. This will raise a Python
+// exception when the stack has likely overwritten a portio of the heap.
+void assert_heap_ok(void);
 
 #endif  // MICROPY_INCLUDED_SUPERVISOR_STACK_H