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17 changes: 17 additions & 0 deletions
17
analyzers/its/expected/Automapper/AutoMapper--net461-S2445.json
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{ | ||
"issues": [ | ||
{ | ||
"id": "S2445", | ||
"message": "Do not lock on local variable 'typeMap', use a readonly field instead.", | ||
"location": { | ||
"uri": "sources\Automapper\src\AutoMapper\Configuration\MapperConfiguration.cs", | ||
"region": { | ||
"startLine": 256, | ||
"startColumn": 27, | ||
"endLine": 256, | ||
"endColumn": 34 | ||
} | ||
} | ||
} | ||
] | ||
} |
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analyzers/its/expected/Automapper/AutoMapper--netstandard2.0-S2445.json
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{ | ||
"issues": [ | ||
{ | ||
"id": "S2445", | ||
"message": "Do not lock on local variable 'typeMap', use a readonly field instead.", | ||
"location": { | ||
"uri": "sources\Automapper\src\AutoMapper\Configuration\MapperConfiguration.cs", | ||
"region": { | ||
"startLine": 256, | ||
"startColumn": 27, | ||
"endLine": 256, | ||
"endColumn": 34 | ||
} | ||
} | ||
} | ||
] | ||
} |
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{ | ||
"issues": [ | ||
{ | ||
"id": "S2445", | ||
"message": "Do not lock on writable field 'entitiesLock', use a readonly field instead.", | ||
"location": { | ||
"uri": "sources\Nancy\src\Nancy\Helpers\HttpEncoder.cs", | ||
"region": { | ||
"startLine": 62, | ||
"startColumn": 23, | ||
"endLine": 62, | ||
"endColumn": 35 | ||
} | ||
} | ||
} | ||
] | ||
} |
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17
analyzers/its/expected/Nancy/Nancy--netstandard2.0-S2445.json
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{ | ||
"issues": [ | ||
{ | ||
"id": "S2445", | ||
"message": "Do not lock on writable field 'entitiesLock', use a readonly field instead.", | ||
"location": { | ||
"uri": "sources\Nancy\src\Nancy\Helpers\HttpEncoder.cs", | ||
"region": { | ||
"startLine": 62, | ||
"startColumn": 23, | ||
"endLine": 62, | ||
"endColumn": 35 | ||
} | ||
} | ||
} | ||
] | ||
} |
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<p>Locking on a class field synchronizes not on the field itself, but on the object assigned to it. Thus, there are some good practices to follow to | ||
avoid bugs related to thread synchronization.</p> | ||
<ol> | ||
<li> Locking on a non-<code>readonly</code> field makes it possible for the field’s value to change while a thread is in the code block locked on | ||
the old value. This allows another thread to lock on the new value and access the same block concurrently. </li> | ||
<li> Locking on a local variable or a new instance of an object can undermine synchronization because two different threads running the same method | ||
in parallel will potentially lock on different instances of the same object, allowing them to access the synchronized block at the same time. </li> | ||
<li> Locking on a string literal is also dangerous since, depending on whether the string is interned or not, different threads may or may not | ||
synchronize on the same object instance. </li> | ||
</ol> | ||
<h2>Noncompliant Code Example</h2> | ||
<pre> | ||
private Color color = new Color("red"); | ||
private readonly string colorString = "red"; | ||
|
||
private void DoSomething() | ||
{ | ||
// Synchronizing access via "color" | ||
lock (color) // Noncompliant; lock is actually on object instance "red" referred to by the "color" field | ||
{ | ||
//... | ||
color = new Color("green"); // other threads now allowed into this block | ||
// ... | ||
} | ||
lock (new object()) // Noncompliant; this is a no-op | ||
{ | ||
// ... | ||
} | ||
lock (colorString) // Noncompliant; strings can be interned | ||
{ | ||
// ... | ||
} | ||
} | ||
</pre> | ||
<h2>Compliant Solution</h2> | ||
<pre> | ||
private Color color = new Color("red"); | ||
private readonly object lockObj = new object(); | ||
|
||
private void DoSomething() | ||
{ | ||
lock (lockObj) | ||
{ | ||
//... | ||
color = new Color("green"); | ||
// ... | ||
} | ||
} | ||
</pre> | ||
<h2>See</h2> | ||
<ul> | ||
<li> <a href="https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/statements/lock">Lock Statement</a> - lock statement - ensure | ||
exclusive access to a shared resource </li> | ||
<li> <a href="https://learn.microsoft.com/en-us/dotnet/api/system.string.intern">String.Intern</a> - <code>String.Intern(String)</code> Method </li> | ||
<li> <a href="https://cwe.mitre.org/data/definitions/412">MITRE, CWE-412</a> - Unrestricted Externally Accessible Lock </li> | ||
<li> <a href="https://cwe.mitre.org/data/definitions/413">MITRE, CWE-413</a> - Improper Resource Locking </li> | ||
</ul> | ||
|
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{ | ||
"title": "Blocks should be synchronized on read-only fields", | ||
"type": "BUG", | ||
"status": "ready", | ||
"remediation": { | ||
"func": "Constant\/Issue", | ||
"constantCost": "15min" | ||
}, | ||
"tags": [ | ||
"cwe", | ||
"multi-threading" | ||
], | ||
"defaultSeverity": "Major", | ||
"ruleSpecification": "RSPEC-2445", | ||
"sqKey": "S2445", | ||
"scope": "All", | ||
"securityStandards": { | ||
"CWE": [ | ||
412, | ||
413 | ||
] | ||
}, | ||
"quickfix": "unknown" | ||
} |
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|
@@ -99,6 +99,7 @@ | |
"S2386", | ||
"S2436", | ||
"S2437", | ||
"S2445", | ||
"S2479", | ||
"S2486", | ||
"S2551", | ||
|
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analyzers/src/SonarAnalyzer.CSharp/Rules/LockedFieldShouldBeReadonly.cs
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/* | ||
* SonarAnalyzer for .NET | ||
* Copyright (C) 2015-2023 SonarSource SA | ||
* mailto: contact AT sonarsource DOT com | ||
* | ||
* This program is free software; you can redistribute it and/or | ||
* modify it under the terms of the GNU Lesser General Public | ||
* License as published by the Free Software Foundation; either | ||
* version 3 of the License, or (at your option) any later version. | ||
* | ||
* This program is distributed in the hope that it will be useful, | ||
* but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
* Lesser General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU Lesser General Public License | ||
* along with this program; if not, write to the Free Software Foundation, | ||
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | ||
*/ | ||
|
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namespace SonarAnalyzer.Rules.CSharp; | ||
|
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[DiagnosticAnalyzer(LanguageNames.CSharp)] | ||
public sealed class LockedFieldShouldBeReadonly : SonarDiagnosticAnalyzer | ||
{ | ||
private const string DiagnosticId = "S2445"; | ||
|
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private static readonly DiagnosticDescriptor Rule = DescriptorFactory.Create(DiagnosticId, "Do not lock on {0}, use a readonly field instead."); | ||
|
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public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics => ImmutableArray.Create(Rule); | ||
|
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protected override void Initialize(SonarAnalysisContext context) => | ||
context.RegisterNodeAction(CheckLockStatement, SyntaxKind.LockStatement); | ||
|
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private static void CheckLockStatement(SonarSyntaxNodeReportingContext context) | ||
{ | ||
var expression = ((LockStatementSyntax)context.Node).Expression?.RemoveParentheses(); | ||
if (IsCreation(expression)) | ||
{ | ||
ReportIssue("a new instance because is a no-op"); | ||
} | ||
else | ||
{ | ||
var lazySymbol = new Lazy<ISymbol>(() => context.SemanticModel.GetSymbolInfo(expression).Symbol); | ||
if (IsOfTypeString(expression, lazySymbol)) | ||
{ | ||
ReportIssue("strings as they can be interned"); | ||
} | ||
else if (expression is IdentifierNameSyntax && lazySymbol.Value is ILocalSymbol localSymbol) | ||
{ | ||
ReportIssue($"local variable '{localSymbol.Name}'"); | ||
} | ||
else if (FieldWritable(expression, lazySymbol) is { } field) | ||
{ | ||
ReportIssue($"writable field '{field.Name}'"); | ||
} | ||
} | ||
|
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void ReportIssue(string message) => | ||
context.ReportIssue(Diagnostic.Create(Rule, expression.GetLocation(), message)); | ||
} | ||
|
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private static bool IsCreation(ExpressionSyntax expression) => | ||
expression.IsAnyKind( | ||
SyntaxKind.ObjectCreationExpression, | ||
SyntaxKind.AnonymousObjectCreationExpression, | ||
SyntaxKind.ArrayCreationExpression, | ||
SyntaxKind.ImplicitArrayCreationExpression, | ||
SyntaxKind.QueryExpression); | ||
|
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private static bool IsOfTypeString(ExpressionSyntax expression, Lazy<ISymbol> lazySymbol) => | ||
expression.IsAnyKind(SyntaxKind.StringLiteralExpression, SyntaxKind.InterpolatedStringExpression) | ||
|| lazySymbol.Value.GetSymbolType().Is(KnownType.System_String); | ||
|
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private static IFieldSymbol FieldWritable(ExpressionSyntax expression, Lazy<ISymbol> lazySymbol) => | ||
expression.IsAnyKind(SyntaxKind.IdentifierName, SyntaxKind.SimpleMemberAccessExpression) && lazySymbol.Value is IFieldSymbol lockedField && !lockedField.IsReadOnly | ||
? lockedField | ||
: null; | ||
} |
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54 changes: 54 additions & 0 deletions
54
analyzers/tests/SonarAnalyzer.UnitTest/Rules/LockedFieldShouldBeReadonlyTest.cs
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/* | ||
* SonarAnalyzer for .NET | ||
* Copyright (C) 2015-2023 SonarSource SA | ||
* mailto: contact AT sonarsource DOT com | ||
* | ||
* This program is free software; you can redistribute it and/or | ||
* modify it under the terms of the GNU Lesser General Public | ||
* License as published by the Free Software Foundation; either | ||
* version 3 of the License, or (at your option) any later version. | ||
* | ||
* This program is distributed in the hope that it will be useful, | ||
* but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
* Lesser General Public License for more details. | ||
* | ||
* You should have received a copy of the GNU Lesser General Public License | ||
* along with this program; if not, write to the Free Software Foundation, | ||
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | ||
*/ | ||
|
||
using SonarAnalyzer.Rules.CSharp; | ||
|
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namespace SonarAnalyzer.UnitTest.Rules; | ||
|
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[TestClass] | ||
public class LockedFieldShouldBeReadonlyTest | ||
{ | ||
private readonly VerifierBuilder builder = new VerifierBuilder<LockedFieldShouldBeReadonly>(); | ||
|
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[TestMethod] | ||
public void LockedFieldShouldBeReadonly_CS() => | ||
builder.AddPaths("LockedFieldShouldBeReadonly.cs").Verify(); | ||
|
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[TestMethod] | ||
public void LockedFieldShouldBeReadonly_CSharp8() => | ||
builder | ||
.AddPaths("LockedFieldShouldBeReadonly.CSharp8.cs") | ||
.WithOptions(ParseOptionsHelper.FromCSharp8) | ||
.Verify(); | ||
|
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[TestMethod] | ||
public void LockedFieldShouldBeReadonly_CSharp9() => | ||
builder | ||
.AddPaths("LockedFieldShouldBeReadonly.CSharp9.cs") | ||
.WithOptions(ParseOptionsHelper.FromCSharp9) | ||
.Verify(); | ||
|
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[TestMethod] | ||
public void LockedFieldShouldBeReadonly_CSharp11() => | ||
builder | ||
.AddPaths("LockedFieldShouldBeReadonly.CSharp11.cs") | ||
.WithOptions(ParseOptionsHelper.FromCSharp11) | ||
.Verify(); | ||
} |
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15
analyzers/tests/SonarAnalyzer.UnitTest/TestCases/LockedFieldShouldBeReadonly.CSharp11.cs
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using System; | ||
|
||
class Test | ||
{ | ||
void OnANewInstance() | ||
{ | ||
lock ("""a raw string literal""") { } // Noncompliant | ||
lock ($"""an interpolated {"raw string literal"}""") { } // Noncompliant | ||
} | ||
|
||
void TargetTypedObjectCreation() | ||
{ | ||
lock (new() as Tuple<int>) { } // Error [CS8754] | ||
} | ||
} |
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45
analyzers/tests/SonarAnalyzer.UnitTest/TestCases/LockedFieldShouldBeReadonly.CSharp8.cs
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class Test | ||
{ | ||
static readonly object staticReadonlyField = null; | ||
|
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readonly object readonlyField = null; | ||
object readWriteField = null; | ||
|
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Test() | ||
{ | ||
ref object refToReadonlyField = ref readonlyField; | ||
lock (refToReadonlyField) { } // Noncompliant, while the reference is to a readonly field, the reference itself is a local variable and as of C# 7.3 can be ref reassigned | ||
|
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ref object refToReadWriteField = ref readWriteField; | ||
lock (refToReadWriteField) { } // Noncompliant | ||
} | ||
|
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void ReadonlyReferences() | ||
{ | ||
lock (RefReturnReadonlyField(this)) { } | ||
lock (RefReturnStaticReadonlyField()) { } | ||
lock (StaticRefReturnReadonlyField(this)) { } | ||
lock (StaticRefReturnStaticReadonlyField()) { } | ||
|
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ref readonly object RefReturnReadonlyField(Test instance) => ref instance.readonlyField; | ||
ref readonly object RefReturnStaticReadonlyField() => ref Test.staticReadonlyField; | ||
static ref readonly object StaticRefReturnReadonlyField(Test instance) => ref instance.readonlyField; | ||
static ref readonly object StaticRefReturnStaticReadonlyField() => ref Test.staticReadonlyField; | ||
} | ||
|
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void OnANewInstanceOnStack() | ||
{ | ||
lock (stackalloc int[] { }) { } // Error [CS0185] | ||
lock (stackalloc [] { 1 }) { } // Error [CS0185] | ||
} | ||
|
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void CoalescingAssignment(object oPar) | ||
{ | ||
lock (oPar ??= readonlyField) { } // FN, null conditional assignment not supported | ||
} | ||
|
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void SwitchExpression(object oPar) | ||
{ | ||
lock (oPar switch { _ => new object() }) { } // FN, switch expression not supported | ||
} | ||
} |
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analyzers/tests/SonarAnalyzer.UnitTest/TestCases/LockedFieldShouldBeReadonly.CSharp9.cs
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class Test | ||
{ | ||
readonly ARecord readonlyField = new(); | ||
ARecord readWriteField = new(); | ||
|
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static readonly ARecord staticReadonlyField = new(); | ||
static ARecord staticReadWriteField = new(); | ||
|
||
void OnAFieldOfTypeRecord() | ||
{ | ||
lock (readonlyField) { } | ||
lock (readWriteField) { } // Noncompliant | ||
lock (staticReadonlyField) { } | ||
lock (staticReadWriteField) { } // Noncompliant | ||
} | ||
|
||
void OnANewRecordInstance() | ||
{ | ||
lock (new ARecord()) { } // Noncompliant | ||
} | ||
|
||
record ARecord(); | ||
} |
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