[release/v7.6] Close pipe client handles after creating the child ssh process #26564
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adityapatwardhan
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CL-General
adityapatwardhan
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TravisEz13 and
daxian-dbw
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Pull request overview
This is a backport of PR #26491 to the release/v7.6 branch, fixing a critical SSH remoting hang on Windows. The core issue was that pipe client handles were not being properly closed after creating the SSH child process, preventing stdout/stderr reader threads from completing when SSH exits. This caused indefinite hangs when using Invoke-Command -HostName or New-PSSession -HostName on Windows.
Key Changes:
- Fixed pipe client handle cleanup by adding
lpStartupInfo.Dispose()to the finally block, ensuring client handles are always closed after process creation - Fixed two critical copy-paste bugs where
stdInWriterVarwas being disposed instead ofstdOutReaderVarandstdErrReaderVar - Added comprehensive tests to verify PowerShell doesn't hang on SSH connections to non-existent hosts
- Refactored namespace references and improved code clarity with modern C# patterns
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| test/powershell/engine/Remoting/SSHRemotingCmdlets.Tests.ps1 | Adds new tests to verify no hangs occur when connecting to non-existent SSH hosts with both New-PSSession and Invoke-Command |
| src/System.Management.Automation/engine/remoting/fanin/OutOfProcTransportManager.cs | Simplifies namespace references and corrects type alias from FormattedErrorTextWriter to OutOfProcessTextWriter for error prefix checks |
| src/System.Management.Automation/engine/remoting/common/RunspaceConnectionInfo.cs | Implements the core fix by ensuring pipe client handles are disposed via lpStartupInfo.Dispose() in the finally block; fixes critical disposal bugs; modernizes code with pattern matching and namespace simplifications |
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daxian-dbw
approved these changes
Dec 2, 2025
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Backport of #26491 to release/v7.6
Triggered by @adityapatwardhan on behalf of @daxian-dbw
Original CL Label: CL-General
/cc @PowerShell/powershell-maintainers
Impact
REQUIRED: Choose either Tooling Impact or Customer Impact (or both). At least one checkbox must be selected.
Tooling Impact
Customer Impact
Fixes critical SSH connection hangs on Windows. When running Invoke-Command -HostName or New-PSSession -HostName on Windows, PowerShell would hang indefinitely due to pipe client handles not being closed after creating the ssh.exe process. This prevents the stdout/stderr reader threads from completing when SSH exits.
Regression
REQUIRED: Check exactly one box.
This is not a regression.
Testing
Original PR added tests to verify PowerShell doesn't hang on SSH connections to non-existent hosts. Backport verified by running the new tests on release/v7.6 branch and confirming the fix resolves the Windows-specific SSH hang issue.
Risk
REQUIRED: Check exactly one box.
Medium risk - affects SSH remoting functionality which is commonly used, but the fix is well-scoped to handle cleanup and has comprehensive test coverage. The change only affects the Windows-specific SSH connection code path.