Fix StackOverflow in CfgAllPathValidator.AreAllSuccessorsValid

analyzers/src/SonarAnalyzer.CFG/Roslyn/CfgAllPathValidator.cs

@@ -23,29 +23,43 @@ namespace SonarAnalyzer.CFG.Roslyn
     public abstract class CfgAllPathValidator
     {
         private readonly ControlFlowGraph cfg;
-        private readonly Dictionary<BasicBlock, bool> visitedStatus = new Dictionary<BasicBlock, bool>();
 
         protected abstract bool IsValid(BasicBlock block);
         protected abstract bool IsInvalid(BasicBlock block);
 
         protected CfgAllPathValidator(ControlFlowGraph cfg) =>
             this.cfg = cfg;
 
-        public bool CheckAllPaths() =>
-            IsBlockOrAllSuccessorsValid(cfg.EntryBlock);
-
-        private bool IsBlockOrAllSuccessorsValid(BasicBlock block)
-        {
-            var isValid = !IsInvalid(block) && (IsValid(block) || AreAllSuccessorsValid(block));
-            visitedStatus[block] = isValid;
-            return isValid;
-        }
-
-        private bool AreAllSuccessorsValid(BasicBlock block)
+        public bool CheckAllPaths()
         {
-            visitedStatus[block] = true; // protects from loops, don't fail the computation if hits itself
-            return block.SuccessorBlocks.Any()
-                   && block.SuccessorBlocks.All(x => x != cfg.ExitBlock && (visitedStatus.ContainsKey(x) ? visitedStatus[x] : IsBlockOrAllSuccessorsValid(x)));
+            HashSet<BasicBlock> visited = [];
+            var blocks = new Stack<BasicBlock>();
+            blocks.Push(cfg.EntryBlock);
+            while (blocks.Count > 0)
+            {
+                var block = blocks.Pop();
+                if (!visited.Add(block))
+                {
+                    continue; // We already visited this block. (This protects from endless loops)
+                }
+                if (block == cfg.ExitBlock || IsInvalid(block))
+                {
+                    return false;
+                }
+                if (IsValid(block))
+                {
+                    continue;
+                }
+                if (block.SuccessorBlocks.IsEmpty)
+                {
+                    return false;
+                }
+                foreach (var successorBlock in block.SuccessorBlocks)
+                {
+                    blocks.Push(successorBlock);
+                }
+            }
+            return true;
         }
     }
 }

analyzers/tests/SonarAnalyzer.Test/Rules/InfiniteRecursionTest.cs

@@ -18,6 +18,7 @@
  * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
+using System.Text;
 using SonarAnalyzer.Rules.CSharp;
 
 namespace SonarAnalyzer.Test.Rules
@@ -60,5 +61,100 @@ public class InfiniteRecursionTest
 
 #endif
 
+        // https://github.com/SonarSource/sonar-dotnet/issues/8977
+        [TestMethod]
+        public void InfiniteRecursion_RoslynCfg_8977()
+        {
+            const int rows = 4_000;
+            var code = new StringBuilder();
+            code.Append("""
+            using UInt32Value = System.UInt32;
+            using StringValue = System.String;
+
+            public class WorksheetPart
+            {
+                public Worksheet Worksheet { get; set; }
+            }
+            public class Worksheet
+            {
+                public MarkupCompatibilityAttributes MCAttributes { get; set; }
+                public void AddNamespaceDeclaration(string alias, string xmlNamespace) { }
+                public void Append(SheetData sheetData1) { }
+            }
+            public class SheetData
+            {
+                public void Append(Row r) { }
+            }
+            public class MarkupCompatibilityAttributes
+            {
+                public string Ignorable { get; set; }
+            }
+            public class Row
+            {
+                public UInt32Value RowIndex { get; set; }
+                public ListValue<StringValue> Spans { get; set; }
+                public double DyDescent { get; set; }
+                public void Append(Cell c) { }
+            }
+            public class ListValue<T>
+            {
+                public string InnerText { get; set; }
+            }
+            public class Cell
+            {
+                public string CellReference { get; set; }
+                public UInt32Value StyleIndex { get; set; }
+                public void Append(CellValue c) { }
+            }
+            public class CellValue
+            {
+                public string Text { get; set; }
+            }
+
+            class Program
+            {
+                public static void Main() { }
+
+                void GenerateWorksheetPart1Content(WorksheetPart worksheetPart1)
+                {
+                    Worksheet worksheet1 = new Worksheet() { MCAttributes = new MarkupCompatibilityAttributes() { Ignorable = "x14ac xr xr2 xr3" } };
+                    worksheet1.AddNamespaceDeclaration("r", "http://schemas.openxmlformats.org/officeDocument/2006/relationships");
+                    worksheet1.AddNamespaceDeclaration("mc", "http://schemas.openxmlformats.org/markup-compatibility/2006");
+                    worksheet1.AddNamespaceDeclaration("x14ac", "http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac");
+                    worksheet1.AddNamespaceDeclaration("xr", "http://schemas.microsoft.com/office/spreadsheetml/2014/revision");
+                    worksheet1.AddNamespaceDeclaration("xr2", "http://schemas.microsoft.com/office/spreadsheetml/2015/revision2");
+                    worksheet1.AddNamespaceDeclaration("xr3", "http://schemas.microsoft.com/office/spreadsheetml/2016/revision3");
+
+                    SheetData sheetData1 = new SheetData();
+            """);
+            for (var i = 1; i <= rows; i++)
+            {
+                code.Append($$"""
+                    Row row{{i}} = new Row() { RowIndex = (UInt32Value)1U, Spans = new ListValue<StringValue>() { InnerText = "1:1" }, DyDescent = 0.25D };
+
+                    Cell cell{{i}} = new Cell() { CellReference = "A{{i}}", StyleIndex = (UInt32Value)1U };
+                    CellValue cellValue{{i}} = new CellValue();
+                    cellValue{{i}}.Text = "{{i}}";
+
+                    cell{{i}}.Append(cellValue{{i}});
+
+                    row{{i}}.Append(cell{{i}});
+            """);
+            }
+            for (var i = 1; i <= rows; i++)
+            {
+                code.AppendLine($$"""        sheetData1.Append(row{{i}});""");
+            }
+            code.Append(""""
+                    worksheet1.Append(sheetData1);
+                    worksheetPart1.Worksheet = worksheet1;
+                }
+            }
+            """");
+
+            roslynCfg.AddSnippet(code.ToString())
+                .WithOptions(ParseOptionsHelper.FromCSharp8)
+                .Verify();
+        }
     }
 }