prevent unintended sign extension errors

When an unsigned char is shifted << 24 bits its type will be
promoted to signed 32-bits.   If the value is then assigned to
an unsigned 64-bit value sign extension will occur.

Prevent the unwanted sign extension by explicitly casting the
value to unsigned long before shifting.

Change-Id: Iabeac0f17dc3229a2dc89abe71960a8ffbf523f8

lib/kadm5/ipropd_master.c

@@ -1253,7 +1253,8 @@ fill_input(krb5_context context, slave *s)
             return EWOULDBLOCK;
 
         buf = s->input.header_buf;
-        len = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | buf[3];
+        len = ((unsigned long)buf[0] << 24) | (buf[1] << 16)
+	    | (buf[2] << 8) | buf[3];
         if (len > SLAVE_MSG_MAX)
             return EINVAL;
         ret = krb5_data_alloc(&s->input.packet, len);