- Add IsWin10BuildAtLeast() helper function to check Windows 10 build numbers
- Replace direct build number comparison with IsWin10BuildAtLeast() for ReflectDrivers check
- Update error message to be more specific about Windows version requirement
This update simplifies the logic for detecting active sudo sessions by checking the exit code of the sudo -n -l command, which reliably returns 0 if a session is active.
Additionally, this approach is now applicable to recent macOS versions, as they no longer have the sudo bug that previously prevented us from using this method.
During a Windows upgrade, ownership of veracrypt.sys is set to TrustedInstaller, preventing VeraCrypt from accessing the file during an update.
This commit resolves the issue by temporarily taking ownership of the file to rename it, allowing the new file to be copied. The setup process now obtains additional privileges for this operation, which are properly dropped once the file copying is complete.
- Made the maximum work items count configurable to allow flexibility based on system needs.
- Increased the default value of max work items count to 1024 to better handle high-throughput scenarios.
- Queue write IRPs in system worker thread to avoid potential deadlocks in write scenarios.
Reduce the critical section protected by spinlock to only cover the list manipulation operation. Move the ActiveWorkItems counter decrement outside the spinlock using InterlockedDecrement, and separate event signaling from the locked section.
This change minimizes time spent at raised IRQL (DISPATCH_LEVEL) and reduces potential for lock contention.
There was a deadlock issue in the driver caused by the CompletionThreadProc function in EncryptedIoQueue.c:
https://sourceforge.net/p/veracrypt/discussion/general/thread/f6e7f623d0/?page=20&limit=25#8362
The driver uses a single thread (CompletionThreadProc) to process IRP completions. When IoCompleteRequest is called within this thread, it can result in new IRPs being generated (e.g., for pagefile operations) that are intercepted by the driver and queued back into the CompletionThreadQueue. Since CompletionThreadProc is the only thread processing this queue and is waiting on IoCompleteRequest, these new IRPs are not handled, leading to a system freeze.
To resolve this issue, the following changes have been made:
Deferred IRP Completion Using Pre-allocated Work Items:
- Introduced a pool of pre-allocated work items (COMPLETE_IRP_WORK_ITEM) to handle IRP completions without causing additional resource allocations that could trigger new IRPs.
- The CompletionThreadProc now queues IRP completions to these work items, which are processed in a different context using IoQueueWorkItem, preventing re-entrant IRPs from blocking the completion thread.
Thread-Safe Work Item Pool Management:
- Implemented a thread-safe mechanism using a semaphore (WorkItemSemaphore), spin lock (WorkItemLock), and a free list (FreeWorkItemsList) to manage the pool of work items.
- Threads acquire and release work items safely, and if all work items are busy, threads wait until one becomes available.
Reference Counting and Improved Stop Handling:
- Added an ActiveWorkItems counter to track the number of active work items.
- Modified EncryptedIoQueueStop to wait for all active work items to complete before proceeding with cleanup, ensuring a clean shutdown.
These changes address the deadlock issue by preventing CompletionThreadProc from being blocked by re-entrant IRPs generated during IoCompleteRequest. By deferring IRP completion to a different context using pre-allocated work items and managing resources properly, we avoid the deadlock and ensure that all IRPs are processed correctly.
