TextConsole: saturate escape parameter in TTY_STATE_CSI

Signed-off-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@gmail.com>

console.c

@@ -938,8 +938,11 @@ static void console_putchar(TextConsole *s, int ch)
     case TTY_STATE_CSI: /* handle escape sequence parameters */
         if (ch >= '0' && ch <= '9') {
             if (s->nb_esc_params < MAX_ESC_PARAMS) {
-                s->esc_params[s->nb_esc_params] =
-                    s->esc_params[s->nb_esc_params] * 10 + ch - '0';
+                int *param = &s->esc_params[s->nb_esc_params];
+                int digit = (ch - '0');
+
+                *param = (*param <= (INT_MAX - digit) / 10) ?
+                         *param * 10 + digit : INT_MAX;
             }
         } else {
             if (s->nb_esc_params < MAX_ESC_PARAMS)