Seek and ye shall find

2026-07-08 18:06:41 +00:00 · 2025-09-08 21:41:46 -04:00
parent 5d1f83800b
commit 2ad42e3a0f
2 changed files with 109 additions and 65 deletions
--- a/SabreTools.Serialization/Deserializers/NewExecutable.cs
+++ b/SabreTools.Serialization/Deserializers/NewExecutable.cs
@@ -38,8 +38,13 @@ namespace SabreTools.Serialization.Deserializers

                #region Executable Header

+                // Get the new executable offset
+                long newExeOffset = initialOffset + stub.Header.NewExeHeaderAddr;
+                if (newExeOffset < initialOffset || newExeOffset > data.Length)
+                    return null;
+
                // Try to parse the executable header
-                data.Seek(initialOffset + stub.Header.NewExeHeaderAddr, SeekOrigin.Begin);
+                data.Seek(newExeOffset, SeekOrigin.Begin);
                var header = ParseExecutableHeader(data);
                if (header.Magic != SignatureString)
                    return null;
--- a/SabreTools.Serialization/Deserializers/PortableExecutable.cs
+++ b/SabreTools.Serialization/Deserializers/PortableExecutable.cs
@@ -40,7 +40,13 @@ namespace SabreTools.Serialization.Deserializers

                #region Signature

-                data.Seek(initialOffset + stub.Header.NewExeHeaderAddr, SeekOrigin.Begin);
+                // Get the new executable offset
+                long newExeOffset = initialOffset + stub.Header.NewExeHeaderAddr;
+                if (newExeOffset < initialOffset || newExeOffset > data.Length)
+                    return null;
+
+                // Try to parse the executable header
+                data.Seek(newExeOffset, SeekOrigin.Begin);
                byte[] signature = data.ReadBytes(4);
                executable.Signature = Encoding.ASCII.GetString(signature);
                if (executable.Signature != SignatureString)
@@ -670,10 +676,10 @@ namespace SabreTools.Serialization.Deserializers
            obj.ExportDirectoryTable = directoryTable;

            // Name
-            if (directoryTable.NameRVA.ConvertVirtualAddress(sections) != 0)
+            long nameAddress = initialOffset
+                + directoryTable.NameRVA.ConvertVirtualAddress(sections);
+            if (nameAddress > initialOffset && nameAddress < data.Length)
            {
-                long nameAddress = initialOffset
-                    + directoryTable.NameRVA.ConvertVirtualAddress(sections);
                data.Seek(nameAddress, SeekOrigin.Begin);

                string? name = data.ReadNullTerminatedAnsiString();
@@ -681,10 +687,12 @@ namespace SabreTools.Serialization.Deserializers
            }

            // Address table
-            if (directoryTable.AddressTableEntries != 0 && directoryTable.ExportAddressTableRVA.ConvertVirtualAddress(sections) != 0)
+            long exportAddressTableAddress = initialOffset
+                + directoryTable.ExportAddressTableRVA.ConvertVirtualAddress(sections);
+            if (directoryTable.AddressTableEntries != 0
+                && exportAddressTableAddress > initialOffset
+                && exportAddressTableAddress < data.Length)
            {
-                long exportAddressTableAddress = initialOffset
-                    + directoryTable.ExportAddressTableRVA.ConvertVirtualAddress(sections);
                data.Seek(exportAddressTableAddress, SeekOrigin.Begin);

                var table = new ExportAddressTableEntry[directoryTable.AddressTableEntries];
@@ -698,10 +706,12 @@ namespace SabreTools.Serialization.Deserializers
            }

            // Name pointer table
-            if (directoryTable.NumberOfNamePointers != 0 && directoryTable.NamePointerRVA.ConvertVirtualAddress(sections) != 0)
+            long namePointerTableAddress = initialOffset
+                + directoryTable.NamePointerRVA.ConvertVirtualAddress(sections);
+            if (directoryTable.NumberOfNamePointers != 0
+                && namePointerTableAddress > initialOffset
+                && namePointerTableAddress < data.Length)
            {
-                long namePointerTableAddress = initialOffset
-                    + directoryTable.NamePointerRVA.ConvertVirtualAddress(sections);
                data.Seek(namePointerTableAddress, SeekOrigin.Begin);

                var table = new ExportNamePointerTable();
@@ -717,10 +727,12 @@ namespace SabreTools.Serialization.Deserializers
            }

            // Ordinal table
-            if (directoryTable.NumberOfNamePointers != 0 && directoryTable.OrdinalTableRVA.ConvertVirtualAddress(sections) != 0)
+            long ordinalTableAddress = initialOffset
+                + directoryTable.OrdinalTableRVA.ConvertVirtualAddress(sections);
+            if (directoryTable.NumberOfNamePointers != 0
+                && ordinalTableAddress > initialOffset
+                && ordinalTableAddress < data.Length)
            {
-                long ordinalTableAddress = initialOffset
-                    + directoryTable.OrdinalTableRVA.ConvertVirtualAddress(sections);
                data.Seek(ordinalTableAddress, SeekOrigin.Begin);

                var table = new ExportOrdinalTable();
@@ -743,12 +755,20 @@ namespace SabreTools.Serialization.Deserializers
                table.Strings = new string[directoryTable.NumberOfNamePointers];
                for (int i = 0; i < directoryTable.NumberOfNamePointers; i++)
                {
-                    long nameAddress = initialOffset
+                    long nameTableEntryAddress = initialOffset
                        + obj.NamePointerTable.Pointers[i].ConvertVirtualAddress(sections);
-                    data.Seek(nameAddress, SeekOrigin.Begin);

-                    string? str = data.ReadNullTerminatedAnsiString();
-                    table.Strings[i] = str ?? string.Empty;
+                    if (nameTableEntryAddress > initialOffset && nameTableEntryAddress < data.Length)
+                    {
+                        data.Seek(nameTableEntryAddress, SeekOrigin.Begin);
+
+                        string? str = data.ReadNullTerminatedAnsiString();
+                        table.Strings[i] = str ?? string.Empty;
+                    }
+                    else
+                    {
+                        table.Strings[i] = string.Empty;
+                    }
                }

                obj.ExportNameTable = table;
@@ -930,10 +950,13 @@ namespace SabreTools.Serialization.Deserializers

                long nameAddress = initialOffset
                    + entry.NameRVA.ConvertVirtualAddress(sections);
-                data.Seek(nameAddress, SeekOrigin.Begin);
+                if (nameAddress > initialOffset && nameAddress < data.Length)
+                {
+                    data.Seek(nameAddress, SeekOrigin.Begin);

-                string? name = data.ReadNullTerminatedAnsiString();
-                entry.Name = name;
+                    string? name = data.ReadNullTerminatedAnsiString();
+                    entry.Name = name;
+                }
            }

            // Lookup tables
@@ -950,23 +973,27 @@ namespace SabreTools.Serialization.Deserializers

                long tableAddress = initialOffset
                    + entry.ImportLookupTableRVA.ConvertVirtualAddress(sections);
-                data.Seek(tableAddress, SeekOrigin.Begin);

-                var entryLookupTable = new List<ImportLookupTableEntry>();
-
-                while (true)
+                if (tableAddress > initialOffset && tableAddress < data.Length)
                {
-                    var lookupEntry = ParseImportLookupTableEntry(data, magic);
-                    entryLookupTable.Add(lookupEntry);
+                    data.Seek(tableAddress, SeekOrigin.Begin);

-                    // All zero values means the last entry
-                    if (lookupEntry.OrdinalNameFlag == false
-                        && lookupEntry.OrdinalNumber == 0
-                        && lookupEntry.HintNameTableRVA == 0)
-                        break;
+                    var entryLookupTable = new List<ImportLookupTableEntry>();
+
+                    while (true)
+                    {
+                        var lookupEntry = ParseImportLookupTableEntry(data, magic);
+                        entryLookupTable.Add(lookupEntry);
+
+                        // All zero values means the last entry
+                        if (lookupEntry.OrdinalNameFlag == false
+                            && lookupEntry.OrdinalNumber == 0
+                            && lookupEntry.HintNameTableRVA == 0)
+                            break;
+                    }
+
+                    importLookupTables[i] = [.. entryLookupTable];
                }
-
-                importLookupTables[i] = [.. entryLookupTable];
            }

            obj.ImportLookupTables = importLookupTables;
@@ -985,23 +1012,27 @@ namespace SabreTools.Serialization.Deserializers

                long tableAddress = initialOffset
                    + entry.ImportAddressTableRVA.ConvertVirtualAddress(sections);
-                data.Seek(tableAddress, SeekOrigin.Begin);

-                var addressLookupTable = new List<ImportAddressTableEntry>();
-
-                while (true)
+                if (tableAddress > initialOffset && tableAddress < data.Length)
                {
-                    var tableEntry = ParseImportAddressTableEntry(data, magic);
-                    addressLookupTable.Add(tableEntry);
+                    data.Seek(tableAddress, SeekOrigin.Begin);

-                    // All zero values means the last entry
-                    if (tableEntry.OrdinalNameFlag == false
-                        && tableEntry.OrdinalNumber == 0
-                        && tableEntry.HintNameTableRVA == 0)
-                        break;
+                    var addressLookupTable = new List<ImportAddressTableEntry>();
+
+                    while (true)
+                    {
+                        var tableEntry = ParseImportAddressTableEntry(data, magic);
+                        addressLookupTable.Add(tableEntry);
+
+                        // All zero values means the last entry
+                        if (tableEntry.OrdinalNameFlag == false
+                            && tableEntry.OrdinalNumber == 0
+                            && tableEntry.HintNameTableRVA == 0)
+                            break;
+                    }
+
+                    importAddressTables[i] = [.. addressLookupTable];
                }
-
-                importAddressTables[i] = [.. addressLookupTable];
            }

            obj.ImportAddressTables = importAddressTables;
@@ -1067,10 +1098,14 @@ namespace SabreTools.Serialization.Deserializers
                {
                    long hintNameTableEntryAddress = initialOffset
                        + hintNameTableEntryAddresses[i];
-                    data.Seek(hintNameTableEntryAddress, SeekOrigin.Begin);

-                    var hintNameTableEntry = ParseHintNameTableEntry(data);
-                    importHintNameTable.Add(hintNameTableEntry);
+                    if (hintNameTableEntryAddress > initialOffset && hintNameTableEntryAddress < data.Length)
+                    {
+                        data.Seek(hintNameTableEntryAddress, SeekOrigin.Begin);
+
+                        var hintNameTableEntry = ParseHintNameTableEntry(data);
+                        importHintNameTable.Add(hintNameTableEntry);
+                    }
                }
            }

@@ -1221,7 +1256,7 @@ namespace SabreTools.Serialization.Deserializers

            // Read the data from the offset
            long offset = initialOffset + obj.DataRVA.ConvertVirtualAddress(sections);
-            if (offset > 0 && obj.Size > 0 && offset + (int)obj.Size < data.Length)
+            if (offset > initialOffset && obj.Size > 0 && offset + (int)obj.Size < data.Length)
            {
                data.Seek(offset, SeekOrigin.Begin);
                obj.Data = data.ReadBytes((int)obj.Size);
@@ -1255,14 +1290,14 @@ namespace SabreTools.Serialization.Deserializers
            // Read the name from the offset, if needed
            if (obj.NameOffset > 0)
            {
-                long currentOffset = data.Position;
-
                long nameOffset = tableStart + obj.NameOffset;
-                data.Seek(nameOffset, SeekOrigin.Begin);
-
-                obj.Name = ParseResourceDirectoryString(data);
-
-                data.Seek(currentOffset, SeekOrigin.Begin);
+                if (nameOffset > tableStart && nameOffset < data.Length)
+                {
+                    long currentOffset = data.Position;
+                    data.Seek(nameOffset, SeekOrigin.Begin);
+                    obj.Name = ParseResourceDirectoryString(data);
+                    data.Seek(currentOffset, SeekOrigin.Begin);
+                }
            }

            return obj;
@@ -1325,17 +1360,21 @@ namespace SabreTools.Serialization.Deserializers
                if (entry.DataEntryOffset > 0)
                {
                    long offset = tableStart + entry.DataEntryOffset;
-                    data.Seek(offset, SeekOrigin.Begin);
-
-                    var resourceDataEntry = ParseResourceDataEntry(data, initialOffset, sections);
-                    entry.DataEntry = resourceDataEntry;
+                    if (offset > tableStart && offset < data.Length)
+                    {
+                        data.Seek(offset, SeekOrigin.Begin);
+                        var resourceDataEntry = ParseResourceDataEntry(data, initialOffset, sections);
+                        entry.DataEntry = resourceDataEntry;
+                    }
                }
                else if (entry.SubdirectoryOffset > 0)
                {
                    long offset = tableStart + entry.SubdirectoryOffset;
-                    data.Seek(offset, SeekOrigin.Begin);
-
-                    entry.Subdirectory = ParseResourceDirectoryTable(data, initialOffset, tableStart, sections);
+                    if (offset > tableStart && offset < data.Length)
+                    {
+                        data.Seek(offset, SeekOrigin.Begin);
+                        entry.Subdirectory = ParseResourceDirectoryTable(data, initialOffset, tableStart, sections);
+                    }
                }
            }