From 939c23c03bb645efc71b334293fdb714a477c861 Mon Sep 17 00:00:00 2001
From: Nick Briggs <nicholas.h.briggs@gmail.com>
Date: Thu, 7 Mar 2024 10:01:19 -0800
Subject: [PATCH] Additional check for bad stack offset calculation

Pointer difference calculations on an inappropriate stack pointer could
result in a negative offset, not just an offset that is too large to fit
in 16 bits.  Complain if either case occurs.
---
 inc/adr68k.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/inc/adr68k.h b/inc/adr68k.h
index 9799780..42cae9c 100644
--- a/inc/adr68k.h
+++ b/inc/adr68k.h
@@ -63,8 +63,8 @@ static inline DLword StackOffsetFromNative(void *SAddr)
 {
   /* Stack offsets are expressed as an offset in DLwords from the stack base */
   ptrdiff_t hoffset = (DLword *)SAddr - Stackspace;
-  if (hoffset > 0xffff) {
-    printf("Stack offset is too large: 0x%tx\n", hoffset);
+  if (hoffset > 0xffff || hoffset < 0) {
+    printf("Stack offset is out of range: 0x%tx\n", hoffset);
   }
   return (DLword)hoffset;
 }