April 24, 2026
Homework 10 due Monday
Final exam: 7-10pm April 30, Gilmer 301 (different room!)
Cumulative, see practice tests
Exam conflict form in email
Remember to fill out course evaluations
writepig latin example continued
Consider the following code:
void apply(double (*f)(double), double *l, unsigned n) {
for(int i=0; i<n; i+=1)
l[i] = f(l[i]);
}What are its parameters? How do we call it?
int main() {
double vals[5] = { M_PI, M_E, 2130, 1, 0 };
for(int i=0; i<5; i+=1) printf("%f\t", vals[i]);
puts("");
apply(sqrt, vals, 5);
for(int i=0; i<5; i+=1) printf("%f\t", vals[i]);
puts("");
apply(sin, vals, 5);
for(int i=0; i<5; i+=1) printf("%f\t", vals[i]);
puts("");
apply(cos, vals, 5);
for(int i=0; i<5; i+=1) printf("%f\t", vals[i]);
puts("");
}void apply(double (*f)(double), double *l, unsigned n) {
for(int i=0; i<n; i+=1)
l[i] = f(l[i]);
}double (*f)(double) means:
*f – f is a
pointer
(double) – with a single
double argument
double – that returns a
double
( ) – to make it parse as
*f instead of double *
const char *(*fv)(const char *) = findVowel;
A function pointer is a pointer that references code
In assembly, the address of the function is just a label
Follow calling conventions
Push return address
Jump to that label
C tries to hide that with this function pointer syntax
Be aware of operator precedence!
Vulnerabilities...
...and when to report them
Common Memory Problems (from reading)
Memory leak
Uninitialized memory
Accidental cast-to-pointer
Wrong use of ‘sizeof‘
Unary operator precedence mistakes
Use after free
Stack buffer overflow
Heap buffer overflow
Global buffer overflow
Use after return
Uninitialized pointer
Use after scope
Vulnerability: a program for which something like this could happen (security holes)
Ex: stack buffer overflow possibility
Not necessarily malicious (like when we talked about backdoors)
Exploit: a way to use a vulnerability or backdoor that has been created
Ex: the magic long word to type into our program
Anytime you can modify memory the programmer did not expect you to be able to modify, there’s something you can do to give yourself power or rights the programmer didn’t mean to give you
Common Memory Problems (from reading)
Memory leak
Uninitialized memory
Accidental cast-to-pointer
Wrong use of ‘sizeof‘
Unary operator precedence mistakes
Use after free
Stack buffer overflow
Heap buffer overflow
Global buffer overflow
Use after return
Uninitialized pointer
Use after scope
What should you do when you find a vulnerability?
Good practices when finding a vulnerability:
Tell the owner
Wait (a reasonable amount of time for a fix)
Publish