Challenge 2: A Deliberate Use-After-Free, Caught by AddressSanitizer — Possible Solution
====================================================================

#include <stdlib.h>

int main() {
    int *p = malloc(sizeof(int));
    *p = 42;
    free(p);
    int value = *p;  // deliberate use-after-free
    return value;
}

Compile with ASan and run:

    $ gcc -fsanitize=address -g uaf.c -o uaf
    $ ./uaf

Representative AddressSanitizer output:

    ==12345==ERROR: AddressSanitizer: heap-use-after-free on address 0x...
    READ of size 4 at 0x... thread T0
        #0 0x... in main uaf.c:7
    ...
    freed by thread T0 here:
        #0 0x... in free
        #1 0x... in main uaf.c:6
    ...
    previously allocated by thread T0 here:
        #0 0x... in malloc
        #1 0x... in main uaf.c:4

WHY THIS WORKS AS AN ANSWER
------------------------------
ASan's report identifies the exact bug type (heap-use-after-free),
the exact line of the bad READ (line 7), AND -- unlike a plain crash
-- also shows both where the memory was originally allocated (line 4)
and where it was freed (line 6), exactly matching the chapter's claim
that ASan crashes immediately with a detailed report at the precise
moment of the bad access, giving far more diagnostic context than a
generic segfault would.