Windows driver: add safe MapIrpDataBuffer function to prevent rare BSOD when irp->MdlAddress is NULL Introduce MapIrpDataBuffer to handle Direct/Buffered/Neither I/O, probing & locking pages and allocating a temp MDL when needed. Replace blind MmGetSystemAddressForMdlSafe usage. clean up TempUserMdl in OnItemCompleted to avoid crashes when MdlAddress is NULL. Issue reported at https://sourceforge.net/p/veracrypt/discussion/technical/thread/e43bde8d86/