Stack overflow detection in Embedded C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a stack overflow in embedded C?

A stack overflow happens when a program uses more stack memory than is allocated, causing data to overwrite adjacent memory and potentially crash the system.

intermediate

How can you detect a stack overflow in embedded systems?

You can detect stack overflow by placing a known pattern (a 'canary') at the stack boundary and checking if it changes, or by monitoring the stack pointer to ensure it stays within limits.

intermediate

What is a 'stack canary' and how does it help?

A stack canary is a special value placed at the edge of the stack. If this value changes, it means the stack has overflowed and overwritten memory, signaling an error.

beginner

Why is stack overflow detection important in embedded systems?

Because embedded systems often have limited memory and run critical tasks, detecting stack overflow prevents crashes and unpredictable behavior that can cause system failure.

intermediate

What role does the stack pointer play in stack overflow detection?

The stack pointer shows the current top of the stack. Monitoring it helps ensure it does not go beyond the allocated stack memory, which would indicate overflow.

What happens when a stack overflow occurs in embedded C?

A The stack pointer resets automatically

B The program runs faster

C Memory outside the stack is overwritten

D The CPU temperature decreases

Stack overflow causes the program to overwrite memory outside the stack, which can corrupt data or crash the system.

Which method is commonly used to detect stack overflow?

A Using a stack canary value

B Increasing CPU clock speed

C Disabling interrupts

D Using global variables only

A stack canary is a known value placed at the stack boundary to detect overflow if it changes.

What does the stack pointer indicate in embedded systems?

A The CPU temperature

B The size of the heap

C The number of running tasks

D The current top of the stack

The stack pointer points to the current top of the stack in memory.

Why is stack overflow detection critical in embedded systems?

A Because stack overflow improves performance

B Because embedded systems have limited memory and critical tasks

C Because embedded systems have unlimited memory

D Because embedded systems never use the stack

Embedded systems have limited memory and often run important tasks, so detecting overflow prevents failures.

What is a sign that a stack overflow has occurred?

A The stack canary value is changed

B The CPU clock speed increases

C The program uses less memory

D The stack pointer moves down

If the stack canary value is altered, it means the stack overflowed and overwrote that memory.

Explain how a stack canary helps detect stack overflow in embedded C.

Think about a special marker that warns if memory is overwritten.

Describe why monitoring the stack pointer is useful for detecting stack overflow.

Consider what the stack pointer tells us about memory usage.