Second CTFs part

canary/05_cafe_menu/main.c

@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static void setup(void) {
+    setvbuf(stdin, NULL, _IONBF, 0);
+    setvbuf(stdout, NULL, _IONBF, 0);
+    setvbuf(stderr, NULL, _IONBF, 0);
+}
+
+__attribute__((noreturn)) static void win(void) {
+    puts("Chef's special unlocked!");
+    char *argv[] = {"/bin/sh", NULL};
+    execve("/bin/sh", argv, NULL);
+    _exit(0);
+}
+
+static void vuln(void) {
+    struct {
+        char menu[48];
+        volatile unsigned int idx;
+    } data;
+
+    data.idx = 0;
+
+    printf("Enter today's specials (send 0xff to finish):\n");
+
+    while (data.idx < 200) {
+        char c;
+        if (read(STDIN_FILENO, &c, 1) != 1) break;
+        if ((unsigned char)c == 0xff) break;
+        data.menu[data.idx] = c;
+        data.idx++;
+    }
+
+    printf("Menu updated!\n");
+}
+
+int main(void) {
+    setup();
+    printf("Welcome to the Cafe!\n");
+    vuln();
+    return 0;
+}