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Windows: Implement mutex to serialize initialization across multiple VeraCrypt instances

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When multiple VeraCrypt.exe instances were launched simultaneously, race conditions
could occur during the WM_INITDIALOG processing phase, potentially causing application
crashes or hang. This was because the initialization logic handles critical operations
like mounting/unmounting volumes and processing favorite volumes that modify global
system state.

This commit:
- Adds a named local session mutex (MainInitMutex) that serializes the WM_INITDIALOG handler
- Implements proper acquisition and release of the mutex during initialization
- Ensures proper cleanup of mutex resources on application exit
This commit is contained in:
Mounir IDRASSI
2025-05-27 15:18:06 +09:00
parent e14299936b
commit b18c2d3c71
1 changed files with 61 additions and 1 deletions
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62
src/Mount/Mount.c
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@@ -187,6 +187,10 @@ static DWORD LastKnownLogicalDrives;
static volatile LONG FavoriteMountOnGoing = 0;
const wchar_t* MainInitMutexName = L"Local\\VeraCryptMainInit_02B831C5_401D_4A0D_8CC5_98D2C4CEB5F2";
static HANDLE MainInitMutex = NULL; /* Mutex for main dialog WM_INITDIALOG */
static BOOL MainInitMutexAcquired = FALSE; /* TRUE if the main window mutex has been acquired */
static HANDLE TaskBarIconMutex = NULL;
static BOOL MainWindowHidden = FALSE;
static int pwdChangeDlgMode = PCDM_CHANGE_PASSWORD;
@@ -202,6 +206,29 @@ static HMODULE hWtsLib = NULL;
static WTSREGISTERSESSIONNOTIFICATION fnWtsRegisterSessionNotification = NULL;
static WTSUNREGISTERSESSIONNOTIFICATION fnWtsUnRegisterSessionNotification = NULL;
void AcquireMainInitMutex ()
{
if (MainInitMutex && !MainInitMutexAcquired)
{
DWORD dwWaitResult;
dwWaitResult = WaitForSingleObject (MainInitMutex, INFINITE);
if (dwWaitResult == WAIT_OBJECT_0 || dwWaitResult == WAIT_ABANDONED)
{
// Mutex acquired successfully
MainInitMutexAcquired = TRUE;
}
}
}
void ReleaseMainInitMutex ()
{
if (MainInitMutex && MainInitMutexAcquired)
{
ReleaseMutex (MainInitMutex);
MainInitMutexAcquired = FALSE;
}
}
// Used to opt-in to receive notification about power events.
// This is mandatory to support Windows 10 Modern Standby and Windows 8.1 Connected Standby power model.
// https://docs.microsoft.com/en-us/windows-hardware/design/device-experiences/prepare-software-for-modern-standby
@@ -426,6 +453,13 @@ static void localcleanup (void)
}
RandStop (TRUE);
if (MainInitMutex != NULL)
{
ReleaseMainInitMutex ();
CloseHandle (MainInitMutex);
MainInitMutex = NULL;
}
}
#ifndef BS_SPLITBUTTON
@@ -7093,6 +7127,9 @@ BOOL CALLBACK MainDialogProc (HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lPa
bUseSecureDesktop = FALSE;
bUseLegacyMaxPasswordLength = FALSE;
// lock the init mutex
AcquireMainInitMutex ();
ResetWrongPwdRetryCount ();
ExtractCommandLine (hwndDlg, (wchar_t *) lParam);
@@ -7149,7 +7186,8 @@ BOOL CALLBACK MainDialogProc (HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lPa
if (ComServerMode)
{
InitDialog (hwndDlg);
// unlock mutex since we are starting the COM server
ReleaseMainInitMutex ();
if (!ComServerMain ())
{
handleWin32Error (hwndDlg, SRC_POS);
@@ -7532,6 +7570,8 @@ BOOL CALLBACK MainDialogProc (HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lPa
RegisterWtsAndPowerNotification(hwndDlg);
DoPostInstallTasks (hwndDlg);
ResetCurrentDirectory ();
// unlock the init mutex
ReleaseMainInitMutex ();
}
return 0;
@@ -10201,6 +10241,26 @@ int WINAPI wWinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, wchar_t *lpsz
AbortProcess ("NODRIVER");
}
/* Initialize Main mutex */
SECURITY_ATTRIBUTES sa;
SECURITY_DESCRIPTOR sd;
sa.nLength = sizeof(SECURITY_ATTRIBUTES);
sa.lpSecurityDescriptor = &sd;
sa.bInheritHandle = FALSE;
// Initialize a security descriptor with a NULL DACL (everyone full access)
if (InitializeSecurityDescriptor(&sd, SECURITY_DESCRIPTOR_REVISION) &&
SetSecurityDescriptorDacl(&sd, TRUE, NULL, FALSE))
{
// Use the security attributes when creating the mutex
MainInitMutex = CreateMutexW(&sa, FALSE, MainInitMutexName);
}
else
{
// If security descriptor initialization fails, fall back to default security attributes
MainInitMutex = CreateMutexW(NULL, FALSE, MainInitMutexName);
}
/* Create the main dialog box */
DialogBoxParamW (hInstance, MAKEINTRESOURCEW (IDD_MOUNT_DLG), NULL, (DLGPROC) MainDialogProc,
(LPARAM) lpszCommandLine);