@samitouri / QOSAMI-WSL-1 / commits / a454dbd7

Make DrvFs initialization callback lifetime-safe (#41218)

* Make DrvFs initialization callback lifetime-safe Route DrvFs initialization through the owning user session so VM shutdown and replacement are synchronized with callback execution. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 7169104c-ee30-445e-b133-49bfa478ef12 * Validate the DrvFs initialization callback in WslCoreVm::Create Reject an empty callback at VM creation so a missing callback fails deterministically instead of throwing std::bad_function_call from a later process creation path. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 7cf83647-6fbe-47bb-a4df-888a6abed9de --------- Co-authored-by: Ben Hillis <benhill@ntdev.microsoft.com> Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 7169104c-ee30-445e-b133-49bfa478ef12 Copilot-Session: 7cf83647-6fbe-47bb-a4df-888a6abed9de

Ben Hillis committed Aug 20, 2026 at 10:58 UTC a454dbd799fc25955f029dad1bfcb0af5385ad27

4 files changed +48 -25

src/windows/service/exe/LxssUserSession.cpp

+31 -1

@@ -2978,8 +2978,13 @@ void LxssUserSessionImpl::_CreateVm()

2978

2979 m_vmId.store(vmId);

2980

2981 + const auto weakSession = weak_from_this();

2982 + auto initializeDrvFs = [weakSession, vmId](HANDLE userToken) noexcept {

2983 + return s_InitializeDrvFs(weakSession, vmId, userToken);

2984 + };

2985 +

2986 // Create the utility VM and register for callbacks.

2982 - m_utilityVm = WslCoreVm::Create(m_userToken, std::move(config), vmId);

2987 + m_utilityVm = WslCoreVm::Create(m_userToken, std::move(config), vmId, std::move(initializeDrvFs));

2988

2989 if (m_httpProxyStateTracker)

2990 {

@@ -4235,6 +4240,31 @@ wil::unique_hkey LxssUserSessionImpl::s_OpenLxssUserKey(_In_ HANDLE UserToken)

4240 return wsl::windows::common::registry::OpenLxssUserKey();

4241 }

4242

4243 +LX_INIT_DRVFS_MOUNT LxssUserSessionImpl::s_InitializeDrvFs(_In_ const std::weak_ptr<LxssUserSessionImpl>& Session, _In_ const GUID& VmId, _In_ HANDLE UserToken) noexcept

4244 +{

4245 + try

4246 + {

4247 + const auto session = Session.lock();

4248 + if (!session)

4249 + {

4250 + return LxInitDrvfsMountNone;

4251 + }

4252 +

4253 + std::lock_guard lock(session->m_instanceLock);

4254 + if (!session->m_utilityVm || !IsEqualGUID(session->m_utilityVm->GetRuntimeId(), VmId))

4255 + {

4256 + return LxInitDrvfsMountNone;

4257 + }

4258 +

4259 + return session->m_utilityVm->InitializeDrvFs(UserToken) ? LxInitDrvfsMountElevated : LxInitDrvfsMountNonElevated;

4260 + }

4261 + catch (...)

4262 + {

4263 + LOG_CAUGHT_EXCEPTION();

4264 + return LxInitDrvfsMountNone;

4265 + }

4266 +}

4267 +

4268 bool LxssUserSessionImpl::s_TerminateInstance(_Inout_ LxssUserSessionImpl* UserSession, _In_ GUID DistroGuid, _In_ bool CheckForClients)

4269 {

4270 bool success = true;

src/windows/service/exe/LxssUserSession.h

+3 -1

@@ -313,7 +313,7 @@ private:

313 /// <summary>

314 /// Each user gets its own LxssUserSessionImpl object, This object manages the lifetime of running instances.

315 /// </summary>

316 -class LxssUserSessionImpl

316 +class LxssUserSessionImpl : public std::enable_shared_from_this<LxssUserSessionImpl>

317 {

318 public:

319 LxssUserSessionImpl(_In_ PSID userSid, _In_ DWORD sessionId, _Inout_ wsl::windows::service::PluginManager& pluginManager);

@@ -772,6 +772,8 @@ private:

772 /// </summary>

773 static wil::unique_hkey s_OpenLxssUserKey(_In_ HANDLE UserToken);

774

775 + static LX_INIT_DRVFS_MOUNT s_InitializeDrvFs(_In_ const std::weak_ptr<LxssUserSessionImpl>& Session, _In_ const GUID& VmId, _In_ HANDLE UserToken) noexcept;

776 +

777 /// <summary>

778 /// Ensures the distribution name is valid.

779 /// </summary>

src/windows/service/exe/WslCoreVm.cpp

+8 -19

@@ -75,17 +75,20 @@ RequiredExtraMmioSpaceForPmemFileInMb(_In_ PCWSTR FilePath)

75 }

76 } // namespace

78 -WslCoreVm::WslCoreVm(_In_ wsl::core::Config&& VmConfig) :

79 - m_vmConfig(std::move(VmConfig)), m_traceClient(m_vmConfig.EnableTelemetry)

78 +WslCoreVm::WslCoreVm(_In_ wsl::core::Config&& VmConfig, _In_ InitializeDrvFsCallback InitializeDrvFs) :

79 + m_vmConfig(std::move(VmConfig)), m_initializeDrvFs(std::move(InitializeDrvFs)), m_traceClient(m_vmConfig.EnableTelemetry)

80 {

81 // Create a job object that will terminate child processes (wslhost.exe, wslrelay.exe)

82 // when the VM is destroyed.

83 m_processJobObject = wsl::windows::common::helpers::CreateKillOnCloseJob();

84 }

86 -std::unique_ptr<WslCoreVm> WslCoreVm::Create(_In_ const wil::shared_handle& UserToken, _In_ wsl::core::Config&& VmConfig, _In_ const GUID& VmId)

86 +std::unique_ptr<WslCoreVm> WslCoreVm::Create(

87 + _In_ const wil::shared_handle& UserToken, _In_ wsl::core::Config&& VmConfig, _In_ const GUID& VmId, _In_ InitializeDrvFsCallback InitializeDrvFs)

88 {

88 - auto newInstance = std::unique_ptr<WslCoreVm>{new WslCoreVm{std::move(VmConfig)}};

89 + THROW_HR_IF(E_INVALIDARG, !InitializeDrvFs);

90 +

91 + auto newInstance = std::unique_ptr<WslCoreVm>{new WslCoreVm{std::move(VmConfig), std::move(InitializeDrvFs)}};

92 try

93 {

94 const auto startTimeMs = GetTickCount64();

@@ -1281,7 +1284,7 @@ std::shared_ptr<LxssRunningInstance> WslCoreVm::CreateInstanceInternal(

1284 localConfig,

1285 DefaultUid,

1286 ClientLifetimeId,

1284 - std::bind(s_InitializeDrvFs, this, std::placeholders::_1),

1287 + m_initializeDrvFs,

1288 featureFlags,

1289 m_vmConfig.DistributionStartTimeout,

1290 m_vmConfig.InstanceIdleTimeout,

@@ -2778,20 +2781,6 @@ std::string WslCoreVm::s_GetMountTargetName(_In_ PCWSTR Disk, _In_opt_ PCWSTR Na

2781 return target;

2782 }

2783

2781 -LX_INIT_DRVFS_MOUNT WslCoreVm::s_InitializeDrvFs(_Inout_ WslCoreVm* VmContext, _In_ HANDLE UserToken)

2782 -{

2783 - try

2784 - {

2785 - return VmContext->InitializeDrvFs(UserToken) ? LxInitDrvfsMountElevated : LxInitDrvfsMountNonElevated;

2786 - }

2787 - catch (...)

2788 - {

2789 - LOG_CAUGHT_EXCEPTION();

2790 -

2791 - return LxInitDrvfsMountNone;

2792 - }

2793 -}

2794 -

2784 void CALLBACK WslCoreVm::s_OnExit(_In_ HCS_EVENT* Event, _In_opt_ void* Context)

2785 try

2786 {

src/windows/service/exe/WslCoreVm.h

+6 -4

@@ -51,7 +51,10 @@ class WslCoreVm

51 void operator=(const WslCoreVm&) = delete;

53 public:

54 - static std::unique_ptr<WslCoreVm> Create(_In_ const wil::shared_handle& UserToken, _In_ wsl::core::Config&& VmConfig, _In_ const GUID& VmId);

54 + using InitializeDrvFsCallback = std::function<LX_INIT_DRVFS_MOUNT(HANDLE)>;

55 +

56 + static std::unique_ptr<WslCoreVm> Create(

57 + _In_ const wil::shared_handle& UserToken, _In_ wsl::core::Config&& VmConfig, _In_ const GUID& VmId, _In_ InitializeDrvFsCallback InitializeDrvFs);

59 ~WslCoreVm() noexcept;

@@ -176,7 +179,7 @@ private:

179 bool operator==(const VirtioFsShare& other) const;

180 };

181

179 - WslCoreVm(_In_ wsl::core::Config&& VmConfig);

182 + WslCoreVm(_In_ wsl::core::Config&& VmConfig, _In_ InitializeDrvFsCallback InitializeDrvFs);

183

184 _Requires_lock_held_(m_guestDeviceLock)

185 void AddDrvFsShare(_In_ bool Admin, _In_ HANDLE UserToken);

@@ -258,8 +261,6 @@ private:

261

262 static std::string s_GetMountTargetName(_In_ PCWSTR Disk, _In_opt_ PCWSTR Name, _In_ int PartitionIndex);

263

261 - static LX_INIT_DRVFS_MOUNT s_InitializeDrvFs(_Inout_ WslCoreVm* VmContext, _In_ HANDLE UserToken);

262 -

264 static void CALLBACK s_OnExit(_In_ HCS_EVENT* Event, _In_opt_ void* Context);

265

266 wil::srwlock m_guestDeviceLock;

@@ -282,6 +283,7 @@ private:

283 std::wstring m_machineId;

284 GUID m_runtimeId;

285 wsl::core::Config m_vmConfig;

286 + InitializeDrvFsCallback m_initializeDrvFs;

287 std::wstring m_comPipe0;

288 std::wstring m_comPipe1;

289 int m_pageReportingOrder;