main_matrix.c

#include <stdio.h>
#include "security_layer.h"

// Low-level function: Calculates the sum of a single row
int calculate_row_sum(int *row, int cols) {
    SHADOW_PROLOGUE(); // Backup the address on entry
    
    int row_total = 0;
    for (int j = 0; j < cols; j++) {
        row_total += row[j];
    }

    SHADOW_EPILOGUE(); // Verify the address on exit
    return row_total;
}

// High-level function: Processes the entire matrix
void sum_matrix(int rows, int cols, int matrix[rows][cols], int trigger_attack) {
    SHADOW_PROLOGUE(); // Pushing high-level function address to shadow stack (index 0)

    printf("Matrix summation process started....\n");
    for (int i = 0; i < rows; i++) {
        // Invoking the sub-function (Address will be added to index 1)
        int r_sum = calculate_row_sum(matrix[i], cols);
        printf("Row %d Sum: %d\n", i, r_sum);

        // Attack Simulation: Corrupting the stack during the 2nd row
        if (trigger_attack && i == 1) {
            printf("\n[Attack] Intercepted during matrix processing! Corrupting the stack...\n");
            unsigned long *ret_addr_ptr = (unsigned long *)__builtin_frame_address(0) + 1;
            *ret_addr_ptr = 0xBADBEEF; 
        }
    }

    SHADOW_EPILOGUE(); // At this point, the shadow stack pointer should return to index 0
}

int main() {
    int my_matrix[3][3] = {
        {1, 2, 3},
        {4, 5, 6},
        {7, 8, 9}
    };

    printf("=== Nested Shadow Stack Test ===\n");

    // Scenario 1: Normal Execution
    printf("\n--- Test 1: Standard Operation ---\n");
    sum_matrix(3, 3, my_matrix, 0);

    // Scenario 2: Attack during nested loop execution
    printf("\n--- Test 2: Attack During Loop Execution ---\n");
    sum_matrix(3, 3, my_matrix, 1);

    return 0;
}