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IL2CPP: Add basic validation to found CodeGenModule pointer (#137)

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This commit is contained in:
Katy Coe
2021-02-12 14:04:11 +01:00
parent 297b3016f8
commit cc0a0718df
2 changed files with 14 additions and 1 deletions
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14
Il2CppInspector.Common/IL2CPP/ImageScan.cs
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@@ -92,6 +92,7 @@ namespace Il2CppInspector
// < 27: mscorlib.dll is always the first CodeGenModule
// >= 27: mscorlib.dll is always the last CodeGenModule (Assembly-CSharp.dll is always the first but non-Unity builds don't have this DLL)
// NOTE: winrt.dll + other DLLs can come after mscorlib.dll so we can't use its location to get an accurate module count
var offsets = FindAllStrings(imageBytes, "mscorlib.dll\0");
vas = offsets.Select(o => Image.MapFileOffsetToVA(o));
@@ -101,10 +102,21 @@ namespace Il2CppInspector
// We'll work back one pointer width at a time trying to find the first CodeGenModule
// Let's hope there aren't more than 200 DLLs in any given application :)
for (int backtrack = 0; backtrack < 200 && (codeRegVas?.Count() ?? 0) != 1; backtrack++) {
var maxCodeGenModules = 200;
for (int backtrack = 0; backtrack < maxCodeGenModules && (codeRegVas?.Count() ?? 0) != 1; backtrack++) {
// Unwind from CodeGenModules + x -> CodeRegistration + y
codeRegVas = FindAllMappedWords(imageBytes, vas);
// The previous word must be the number of CodeGenModules
if (codeRegVas.Count() == 1) {
var codeGenModuleCount = Image.ReadMappedWord(codeRegVas.First() - ptrSize);
// Basic validity check
if (codeGenModuleCount <= 0 || codeGenModuleCount > maxCodeGenModules)
codeRegVas = Enumerable.Empty<ulong>();
}
// Move to the previous CodeGenModule if the above fails
vas = vas.Select(va => va - ptrSize);
}