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Custom rules that don't supply optional properties cause null dereference #1714
Description
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- Make sure you are able to repro it on the latest released version
- Perform a quick search for existing issues to check if this bug has already been reported
Steps to reproduce
Custom rule module:
<#
.SYNOPSIS
Static methods are not allowed in constrained language mode.
.DESCRIPTION
Static methods are not allowed in constrained language mode.
To fix a violation of this rule, use a cmdlet or function instead of a static method.
.EXAMPLE
Test-StaticMethod -CommandAst $CommandAst
.INPUTS
[System.Management.Automation.Language.ScriptBlockAst]
.OUTPUTS
[PSCustomObject[]]
.NOTES
Reference: Output, CLM info.
#>
function Test-StaticMethod
{
[CmdletBinding()]
[OutputType([PSCustomObject[]])]
Param
(
[Parameter(Mandatory = $true)]
[ValidateNotNullOrEmpty()]
[System.Management.Automation.Language.ScriptBlockAst]
$ScriptBlockAst
)
Process
{
try
{
# Gets methods
$invokedMethods = $ScriptBlockAst.FindAll({$args[0] -is [System.Management.Automation.Language.CommandExpressionAst] -and $args[0].Expression -match "^\[.*\]::" },$true)
foreach ($invokedMethod in $invokedMethods)
{
[PSCustomObject]@{Message = “Avoid Using Static Methods”;
Extent = $invokedMethod.Extent;
RuleName = $PSCmdlet.MyInvocation.InvocationName;
Severity = “Warning”}
}
}
catch
{
$PSCmdlet.ThrowTerminatingError($PSItem)
}
}
}Target script:
write-host "test"
$a = "asdf"
$a = $a.replace('s','ssssssss')
[math]::abs(-1)
Function ASDF1234{
"asdf"
} Script analyzer invocation:
Invoke-ScriptAnalyzer -Path 'C:\<path>\CLMTest.ps1' -CustomRulePath 'C:\<path>\MyCustom.psm1' Expected behavior
RuleName Severity ScriptName Line Message
-------- -------- ---------- ---- -------
MyCustom\Test-StaticMethod Warning CLMTest.ps 4 Avoid Using Static Methods
Actual behavior
Invoke-ScriptAnalyzer: Object reference not set to an instance of an object.
Exception :
Type : System.NullReferenceException
TargetSite :
Name : GetExternalRecord
DeclaringType : Microsoft.Windows.PowerShell.ScriptAnalyzer.ScriptAnalyzer
MemberType : Method
Module : Microsoft.Windows.PowerShell.ScriptAnalyzer.dll
Message : Object reference not set to an instance of an object.
Source : Microsoft.Windows.PowerShell.ScriptAnalyzer
HResult : -2147467261
StackTrace :
at Microsoft.Windows.PowerShell.ScriptAnalyzer.ScriptAnalyzer.GetExternalRecord(Ast ast, Token[]
token, ExternalRule[] rules, String filePath) in C:\Users\Robert
Holt\Documents\Dev\Microsoft\PSScriptAnalyzer\Engine\ScriptAnalyzer.cs:line 1291
TargetObject : Microsoft.Windows.PowerShell.ScriptAnalyzer.ScriptAnalyzer
CategoryInfo : NotSpecified: (Microsoft.Windows.P…yzer.ScriptAnalyzer:ScriptAnalyzer)
[Invoke-ScriptAnalyzer], NullReferenceException
FullyQualifiedErrorId :
80004003,Microsoft.Windows.PowerShell.ScriptAnalyzer.Commands.InvokeScriptAnalyzerCommand
InvocationInfo :
MyCommand : Invoke-ScriptAnalyzer
ScriptLineNumber : 1
OffsetInLine : 1
HistoryId : 9
Line : Invoke-ScriptAnalyzer -Path .\CLMTest.ps1 -CustomRulePath .\MyCustom.psm1
PositionMessage : At line:1 char:1
+ Invoke-ScriptAnalyzer -Path .\CLMTest.ps1 -CustomRulePath .\MyCustom. …
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
InvocationName : Invoke-ScriptAnalyzer
CommandOrigin : Internal
ScriptStackTrace : at <ScriptBlock>, <No file>: line 1
PipelineIterationInfo :
The issue lies here:
PSScriptAnalyzer/Engine/ScriptAnalyzer.cs
Lines 1287 to 1292 in 8db488d
When properties are not in the returned object, they surface as null and we need to defend against that.
Activity
rjmholt commentedon Sep 16, 2021
Curiously this code hasn't changed in 6 years, which makes me wonder whether a change has occurred in PowerShell instead...
rjmholt commentedon Sep 16, 2021
Reproduces in Windows PowerShell as well, so looks like no