Stack end 4 bytes below initial SP, not 1

src/canary.rs

@@ -69,9 +69,7 @@ impl Canary {
         }
 
         let stack_start = *stack_info.range.start();
-        // add 1 to end up with the initial stack pointer, which is always 4-byte-aligned
-        let stack_end = *stack_info.range.end() + 1;
-        let stack_available = stack_end - stack_start;
+        let stack_available = *stack_info.range.end() - stack_start;
 
         let size = if measure_stack {
             // When measuring stack consumption, we have to color the whole stack.

src/target_info.rs

@@ -73,8 +73,8 @@ fn extract_stack_info(elf: &Elf, ram_range: &Range<u32>) -> Option<StackInfo> {
 
     let initial_stack_pointer = elf.vector_table.initial_stack_pointer;
 
-    // SP points one past the end of the stack.
-    let mut stack_range = ram_range.start..=initial_stack_pointer - 1;
+    // SP points one word (4-byte) past the end of the stack.
+    let mut stack_range = ram_range.start..=initial_stack_pointer - 4;
 
     for section in elf.sections() {
         let size: u32 = section.size().try_into().expect("expected 32-bit ELF");