BSOD 0xA (IRQL_NOT_LESS_OR_EQUAL): veracrypt.sys causes NULL Irp->UserEvent dereference in KeSetEvent during volume mount

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Evaluación

Dificultad
4/5
Tiempo estimado
3-5 días
Aptitud para principiantes
42/100
Tipo de issue
Error
Claridad
Bastante claro
Estado de actividad
Tranquilo
Stack tecnológico
c
Área
operating-systems, security

Línea de trabajo

Start by examining the VeraCrypt driver’s synchronous I/O and completion paths related to volume mounting, then compare the 1.26.24 driver behavior with the release notes for 1.26.29. Use the supplied crash dumps to verify whether the reported UserEvent lifetime and timeout sequence matches the driver code. Done means identifying the faulty path and confirming a fix prevents the reported bugcheck; the issue provides no source file or test entry point.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

bug

In 4 of 5 dumps PROCESS_NAME is VeraCrypt.exe, with veracrypt+0x4e8cc as the direct caller of NtCreateFile. In the 5th dump, PROCESS_NAME is System, with the call coming from mountmgr!ReconcileThisDatabaseWithMasterWorker → mountmgr!OpenRemoteDatabase — Mount Manager reacting to the same volume-arrival event from a different thread.

WinDbg also reports *** WARNING: Unable to verify timestamp for veracrypt.sys in 4 of 5 dumps.

Suspected root cause: Irp->UserEvent is dereferenced at completion time while pointing to invalid/freed memory. This is consistent with a synchronous I/O request issued by veracrypt.sys using a short-lived (likely stack-allocated) KEVENT combined with a finite wait timeout: if the underlying storage stack does not complete the IRP before the timeout expires, veracrypt.sys's wait returns and the event's storage may be reused/invalidated — but without the IRP being cancelled. When the storage stack later does complete that IRP, IopCompleteRequest dereferences the now-invalid UserEvent pointer, causing the crash at DISPATCH_LEVEL (since storage completion typically happens via DPC).

All captured crashes show concurrent FLTMGR!FltpDoFilterNotificationForNewVolume activity (Windows attaching registered minifilters — in our case including a third-party disk-encryption filesystem filter — to the newly-arrived VeraCrypt volume). We believe this is not the root cause itself, but widens the race window described above (more registered minifilters → longer FltpInitInstance → higher chance the storage stack responds after veracrypt.sys's wait has already timed out).

Note: I noticed that 1.26.29 release notes mention "Improve driver I/O handling, including safer request completion" and "Fix rare BSOD issue affecting the VeraCrypt driver" — this may already address this issue. I am upgrading to test and will update this report with the result.

Steps to reproduce

  1. Install VeraCrypt 1.26.24 on a system that also has another disk-encryption
    product's filesystem filter driver installed (in our case: Symantec/Broadcom
    Encryption Desktop — PGPfsfd.sys, PGPwded.sys, Pgpwdefs.sys), on top of an
    Intel VROC RAID storage stack (iaVROC.sys/mpi3drv.sys under storport.sys).
  2. Use the system normally, mounting/dismounting VeraCrypt volumes as usual.
  3. No single specific action reliably triggers the crash — it occurred 5 times
    over approximately 2 days of normal use, always within seconds of volume
    mount/dismount activity (confirmed via PROCESS_NAME and stack trace in all
    5 dumps), not on every single mount.
  4. System bugchecks with IRQL_NOT_LESS_OR_EQUAL (0xA), consistently in
    nt!KeSetEvent as described above.

We do not have a 100%-reliable single-step repro; this report is based on
5 independent crash dumps with identical signatures collected from the same
machine. We suspect the trigger is timing-dependent (a race between the
storage stack completing an I/O request and a synchronous wait timeout in
veracrypt.sys — see root cause analysis above), which would explain why it
doesn't reproduce on every mount.

Screenshots

N/A

122025-31640-01.dmp
122025-32406-01.dmp
122125-32281-01.dmp
122125-32640-01.dmp
122225-32531-01.dmp

Your Environment

Please tell us more about your environment
VeraCrypt version: 1.26.24 (driver timestamp: Thu May 29 09:43:28 2025)
Operating system and version: Windows 11, build 10.0.26100.7462 (24H2)
System type: 64-bit (x64), 24 logical processors, Hyper-V-enlightened guest

Lenguaje dominante
C
Estrellas
11.7k
Forks
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Merge medio
1 d 1 h
PR fusionados (30 d)
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