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[MachO] Handle chained imports with addends #6604

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Apr 28, 2025
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[MachO] Handle chained imports with addends #6604

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71 changes: 47 additions & 24 deletions view/macho/machoview.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3118,45 +3118,67 @@ void MachoView::ParseChainedFixups(MachOHeader& header, linkedit_data_command ch
std::vector<import_entry> importTable;
parentReader.Seek(importsAddress);

auto processChainedImport =
[symbolsAddress, &importTable](
uint64_t ordinal, uint64_t addend, uint32_t nameOffset, bool weak, auto& reader) {
import_entry entry;
entry.lib_ordinal = ordinal;
entry.addend = addend;
entry.weak = weak;

auto nextEntryAddress = reader.GetOffset();
size_t symNameAddr = symbolsAddress + nameOffset;

reader.Seek(symNameAddr);
try
{
string symbolName = reader.ReadCString();
entry.name = symbolName;
}
catch (ReadException& ex)
{
entry.name = "";
}

importTable.push_back(entry);
reader.Seek(nextEntryAddress);
};

switch (fixupsHeader.imports_format)
{
case DYLD_CHAINED_IMPORT:
{
for (size_t i = 0; i < fixupsHeader.imports_count; i++)
{
uint32_t importEntry = parentReader.Read32();
uint64_t nextEntryAddress = parentReader.GetOffset();

dyld_chained_import import = *(reinterpret_cast<dyld_chained_import*>(&importEntry));

import_entry entry;

entry.lib_ordinal = (uint64_t)import.lib_ordinal;
entry.addend = 0;
entry.weak = (import.weak_import == 1);

size_t symNameAddr = symbolsAddress + import.name_offset;

parentReader.Seek(symNameAddr);
try {
string symbolName = parentReader.ReadCString();
entry.name = symbolName;
}
catch (ReadException& ex)
{
entry.name = "";
}

importTable.push_back(entry);
parentReader.Seek(nextEntryAddress);
processChainedImport(import.lib_ordinal, 0, import.name_offset, import.weak_import, parentReader);
}
break;
}
case DYLD_CHAINED_IMPORT_ADDEND:
{
for (size_t i = 0; i < fixupsHeader.imports_count; i++)
{
dyld_chained_import_addend import;
parentReader.Read(&import, sizeof(import));
processChainedImport(import.lib_ordinal, import.addend, import.name_offset, import.weak_import, parentReader);
}
break;
}
case DYLD_CHAINED_IMPORT_ADDEND64:
{
for (size_t i = 0; i < fixupsHeader.imports_count; i++)
{
dyld_chained_import_addend64 import;
parentReader.Read(&import, sizeof(import));
processChainedImport(import.lib_ordinal, import.addend, import.name_offset, import.weak_import, parentReader);
}
break;
}
default:
{
m_logger->LogWarn("Chained Fixups: Unknown import binding format");
m_logger->LogWarn("Chained Fixups: Unknown import binding format %d", fixupsHeader.imports_format);
processBinds = false; // We can still handle rebases.
break;
}
Expand Down Expand Up @@ -3392,6 +3414,7 @@ void MachoView::ParseChainedFixups(MachOHeader& header, linkedit_data_command ch
externReloc.size = m_addressSize;
externReloc.pcRelative = false;
externReloc.external = true;
externReloc.addend = entry.addend;
header.externalRelocations.emplace_back(externReloc, entry.name);
}
else
Expand Down