[Lldb-commits] [lldb] [lldb][FreeBSD] Add dynamic loader handle class for FreeBSD Kernel (PR #67106)

Alex Langford via lldb-commits lldb-commits at lists.llvm.org
Fri Sep 22 15:50:31 PDT 2023


================
@@ -0,0 +1,770 @@
+#include "lldb/Breakpoint/StoppointCallbackContext.h"
+#include "lldb/Core/Debugger.h"
+#include "lldb/Core/Module.h"
+#include "lldb/Core/ModuleSpec.h"
+#include "lldb/Core/PluginManager.h"
+#include "lldb/Core/Section.h"
+#include "lldb/Core/StreamFile.h"
+#include "lldb/Interpreter/OptionValueProperties.h"
+#include "lldb/Symbol/LocateSymbolFile.h"
+#include "lldb/Symbol/ObjectFile.h"
+#include "lldb/Target/OperatingSystem.h"
+#include "lldb/Target/RegisterContext.h"
+#include "lldb/Target/StackFrame.h"
+#include "lldb/Target/Target.h"
+#include "lldb/Target/Thread.h"
+#include "lldb/Target/ThreadPlanRunToAddress.h"
+#include "lldb/Utility/DataBuffer.h"
+#include "lldb/Utility/DataBufferHeap.h"
+#include "lldb/Utility/LLDBLog.h"
+#include "lldb/Utility/Log.h"
+#include "lldb/Utility/State.h"
+
+#include "Plugins/ObjectFile/ELF/ObjectFileELF.h"
+
+#include "DynamicLoaderFreeBSDKernel.h"
+#include <memory>
+#include <mutex>
+
+using namespace lldb;
+using namespace lldb_private;
+
+LLDB_PLUGIN_DEFINE(DynamicLoaderFreeBSDKernel)
+
+void DynamicLoaderFreeBSDKernel::Initialize() {
+  PluginManager::RegisterPlugin(GetPluginNameStatic(),
+                                GetPluginDescriptionStatic(), CreateInstance,
+                                DebuggerInit);
+}
+
+void DynamicLoaderFreeBSDKernel::Terminate() {
+  PluginManager::UnregisterPlugin(CreateInstance);
+}
+
+llvm::StringRef DynamicLoaderFreeBSDKernel::GetPluginDescriptionStatic() {
+  return "The Dynamic Loader Plugin For FreeBSD Kernel";
+}
+
+static bool is_kernel(Module *module) {
+  if (!module)
+    return false;
+
+  ObjectFile *objfile = module->GetObjectFile();
+  if (!objfile)
+    return false;
+  if (objfile->GetType() != ObjectFile::eTypeExecutable)
+    return false;
+  if (objfile->GetStrata() != ObjectFile::eStrataUnknown &&
+      objfile->GetStrata() != ObjectFile::eStrataUser)
+    return false;
+
+  return true;
+}
+
+static bool is_kmod(Module *module) {
+  if (!module)
+    return false;
+  if (!module->GetObjectFile())
+    return false;
+  ObjectFile *objfile = module->GetObjectFile();
+  if (objfile->GetType() != ObjectFile::eTypeObjectFile &&
+      objfile->GetType() != ObjectFile::eTypeSharedLibrary)
+    return false;
+
+  return true;
+}
+
+static bool is_reloc(Module *module) {
+  if (!module)
+    return false;
+  if (!module->GetObjectFile())
+    return false;
+  ObjectFile *objfile = module->GetObjectFile();
+  if (objfile->GetType() != ObjectFile::eTypeObjectFile)
+    return false;
+
+  return true;
+}
+
+// Instantiate Function of the FreeBSD Kernel Dynamic Loader Plugin called when
+// Register the Plugin
+DynamicLoader *
+DynamicLoaderFreeBSDKernel::CreateInstance(lldb_private::Process *process,
+                                           bool force) {
+  // Check the environment when the plugin is not force loaded
+  Log *log = GetLog(LLDBLog::DynamicLoader);
+  LLDB_LOGF(log, "DynamicLoaderFreeBSDKernel::CreateInstance: "
+                 "Try to create instance");
+  if (!force) {
+    Module *exec = process->GetTarget().GetExecutableModulePointer();
+    // Check if the target is kernel
+    if (exec && !is_kernel(exec)) {
+      return nullptr;
+    }
+
+    const llvm::Triple &triple_ref =
+        process->GetTarget().GetArchitecture().GetTriple();
+    if (!triple_ref.isOSFreeBSD()) {
+      return nullptr;
+    }
+  }
+
+  // At this point we have checked the target is a FreeBSD kernel and all we
+  // have to do is to find the kernel address
+  const addr_t kernel_address = FindFreeBSDKernel(process);
+
+  if (CheckForKernelImageAtAddress(process, kernel_address).IsValid())
+    return new DynamicLoaderFreeBSDKernel(process, kernel_address);
+
+  return nullptr;
+}
+
+addr_t
+DynamicLoaderFreeBSDKernel::FindFreeBSDKernel(lldb_private::Process *process) {
+  addr_t kernel_addr = process->GetImageInfoAddress();
+  if (kernel_addr == LLDB_INVALID_ADDRESS)
+    kernel_addr = FindKernelAtLoadAddress(process);
+  return kernel_addr;
+}
+
+// Get the kernel address if the kernel is not loaded with a slide
+addr_t DynamicLoaderFreeBSDKernel::FindKernelAtLoadAddress(
+    lldb_private::Process *process) {
+  Module *exe_module = process->GetTarget().GetExecutableModulePointer();
+
+  if (!is_kernel(exe_module))
+    return LLDB_INVALID_ADDRESS;
+
+  ObjectFile *exe_objfile = exe_module->GetObjectFile();
+
+  if (!exe_objfile->GetBaseAddress().IsValid())
+    return LLDB_INVALID_ADDRESS;
+
+  if (CheckForKernelImageAtAddress(
+          process, exe_objfile->GetBaseAddress().GetFileAddress())
+          .IsValid())
+    return exe_objfile->GetBaseAddress().GetFileAddress();
+
+  return LLDB_INVALID_ADDRESS;
+}
+
+// Read ELF header from memry and return
+bool DynamicLoaderFreeBSDKernel::ReadELFHeader(Process *process,
+                                               lldb::addr_t addr,
+                                               llvm::ELF::Elf32_Ehdr &header,
+                                               bool *read_error) {
+  Status error;
+  if (read_error)
+    *read_error = false;
+
+  if (process->ReadMemory(addr, &header, sizeof(header), error) !=
+      sizeof(header)) {
+    if (read_error)
+      *read_error = true;
+    return false;
+  }
+
+  if (!header.checkMagic())
+    return false;
+
+  return true;
+}
+
+// Check the correctness of Kernel and return UUID
+lldb_private::UUID DynamicLoaderFreeBSDKernel::CheckForKernelImageAtAddress(
+    Process *process, lldb::addr_t addr, bool *read_error) {
+  Log *log = GetLog(LLDBLog::DynamicLoader);
+
+  if (addr == LLDB_INVALID_ADDRESS) {
+    if (read_error)
+      *read_error = true;
+    return UUID();
+  }
+
+  LLDB_LOGF(log,
+            "DynamicLoaderFreeBSDKernel::CheckForKernelImageAtAddress: "
+            "looking for kernel binary at 0x%" PRIx64,
+            addr);
+
+  llvm::ELF::Elf32_Ehdr header;
+  if (!ReadELFHeader(process, addr, header))
+    return UUID();
+
+  // Check header type
+  if (header.e_type != llvm::ELF::ET_EXEC)
+    return UUID();
+
+  ModuleSP memory_module_sp =
+      process->ReadModuleFromMemory(FileSpec("temp_freebsd_kernel"), addr);
+  if (!memory_module_sp.get())
+    return UUID();
+
+  ObjectFile *exe_objfile = memory_module_sp->GetObjectFile();
+  if (exe_objfile == nullptr) {
+    LLDB_LOGF(log,
+              "DynamicLoaderFreeBSDKernel::CheckForKernelImageAtAddress "
+              "found a binary at 0x%" PRIx64
+              " but could not create an object file from memory",
+              addr);
+    return UUID();
+  }
+
+  if (is_kernel(memory_module_sp.get())) {
+    ArchSpec kernel_arch(
+        llvm::ELF::convertEMachineToArchName(header.e_machine));
+
+    if (!process->GetTarget().GetArchitecture().IsCompatibleMatch(kernel_arch))
+      process->GetTarget().SetArchitecture(kernel_arch);
+
+    if (log) {
+      std::string uuid_str;
+      if (memory_module_sp->GetUUID().IsValid()) {
+        uuid_str = "with UUID ";
+        uuid_str += memory_module_sp->GetUUID().GetAsString();
+      } else {
+        uuid_str = "and no LC_UUID found in load commands ";
+      }
+      LLDB_LOGF(log,
+                "DynamicLoaderFreeBSDKernel::CheckForKernelImageAtAddress: "
+                "kernel binary image found at 0x%" PRIx64 " with arch '%s' %s",
+                addr, kernel_arch.GetTriple().str().c_str(), uuid_str.c_str());
+    }
+
+    return memory_module_sp->GetUUID();
+  }
+
+  return UUID();
+}
+
+void DynamicLoaderFreeBSDKernel::DebuggerInit(
+    lldb_private::Debugger &debugger) {}
+
+DynamicLoaderFreeBSDKernel::DynamicLoaderFreeBSDKernel(Process *process,
+                                                       addr_t kernel_address)
+    : DynamicLoader(process), m_process(process),
+      m_linker_file_list_struct_addr(LLDB_INVALID_ADDRESS),
+      m_linker_file_head_addr(LLDB_INVALID_ADDRESS),
+      m_kernel_load_address(kernel_address), m_mutex() {
+  process->SetCanRunCode(false);
+}
+
+DynamicLoaderFreeBSDKernel::~DynamicLoaderFreeBSDKernel() { Clear(true); }
+
+void DynamicLoaderFreeBSDKernel::Update() {
+  LoadKernelModules();
+  SetNotificationBreakPoint();
+}
+
+// Create in memory Module at the load address
+bool DynamicLoaderFreeBSDKernel::KModImageInfo::ReadMemoryModule(
+    lldb_private::Process *process) {
+  Log *log = GetLog(LLDBLog::DynamicLoader);
+  if (m_memory_module_sp)
+    return true;
+  if (m_load_address == LLDB_INVALID_ADDRESS)
+    return false;
+
+  FileSpec file_spec(m_name.c_str());
+
+  ModuleSP memory_module_sp;
+
+  llvm::ELF::Elf32_Ehdr elf_eheader;
+  size_t size_to_read = 512;
+
+  if (ReadELFHeader(process, m_load_address, elf_eheader)) {
+    if (elf_eheader.e_ident[llvm::ELF::EI_CLASS] == llvm::ELF::ELFCLASS32) {
+      size_to_read = sizeof(llvm::ELF::Elf32_Ehdr) +
+                     elf_eheader.e_phnum * elf_eheader.e_phentsize;
+    } else if (elf_eheader.e_ident[llvm::ELF::EI_CLASS] ==
+               llvm::ELF::ELFCLASS64) {
+      llvm::ELF::Elf64_Ehdr elf_eheader;
+      Status error;
+      if (process->ReadMemory(m_load_address, &elf_eheader, sizeof(elf_eheader),
+                              error) == sizeof(elf_eheader))
+        size_to_read = sizeof(llvm::ELF::Elf64_Ehdr) +
+                       elf_eheader.e_phnum * elf_eheader.e_phentsize;
+    }
+  }
+
+  memory_module_sp =
+      process->ReadModuleFromMemory(file_spec, m_load_address, size_to_read);
+
+  if (!memory_module_sp)
+    return false;
+
+  bool this_is_kernel = is_kernel(memory_module_sp.get());
+
+  if (!m_uuid.IsValid() && memory_module_sp->GetUUID().IsValid())
+    m_uuid = memory_module_sp->GetUUID();
+
+  m_memory_module_sp = memory_module_sp;
+  m_is_kernel = this_is_kernel;
+
+  // The kernel binary is from memory
+  if (this_is_kernel) {
+    if (log)
+      LLDB_LOGF(log,
+                "KextImageInfo::ReadMemoryModule read the kernel binary out "
+                "of memory");
+
+    if (memory_module_sp->GetArchitecture().IsValid())
+      process->GetTarget().SetArchitecture(memory_module_sp->GetArchitecture());
+  }
+
+  return true;
+}
+
+bool DynamicLoaderFreeBSDKernel::KModImageInfo::LoadImageUsingMemoryModule(
+    lldb_private::Process *process) {
+  Log *log = GetLog(LLDBLog::DynamicLoader);
+
+  if (IsLoaded())
+    return true;
+
+  Target &target = process->GetTarget();
+
+  if (IsKernel() && m_uuid.IsValid()) {
+    Stream &s = target.GetDebugger().GetOutputStream();
+    s.Printf("Kernel UUID: %s\n", m_uuid.GetAsString().c_str());
+    s.Printf("Load Address: 0x%" PRIx64 "\n", m_load_address);
+  }
+
+  // Test if the module is loaded into the taget,
+  // maybe the module is loaded manually by user by doing target module add
+  // So that we have to create the module manually
+  if (!m_module_sp) {
+    const ModuleList &target_images = target.GetImages();
+    m_module_sp = target_images.FindModule(m_uuid);
+
+    // Search in the file system
+    if (!m_module_sp) {
+      ModuleSpec module_spec(FileSpec(GetPath()), target.GetArchitecture());
+      if (IsKernel()) {
+        Status error;
+        if (Symbols::DownloadObjectAndSymbolFile(module_spec, error, true)) {
+          if (FileSystem::Instance().Exists(module_spec.GetFileSpec()))
+            m_module_sp = std::make_shared<Module>(module_spec.GetFileSpec(),
+                                                   target.GetArchitecture());
+        }
+      }
+
+      if (!m_module_sp)
+        m_module_sp = target.GetOrCreateModule(module_spec, true);
+      if (IsKernel() && !m_module_sp) {
+        Stream &s = target.GetDebugger().GetOutputStream();
+        s.Printf("WARNING: Unable to locate kernel binary on the debugger "
+                 "system.\n");
+      }
+    }
+
+    if (m_module_sp) {
+      // If the file is not kernel or kmod, the target should be loaded once and
+      // don't reload again
+      if (!IsKernel() && !is_kmod(m_module_sp.get())) {
+        ModuleSP existing_module_sp = target.GetImages().FindModule(m_uuid);
+        if (existing_module_sp &&
+            existing_module_sp->IsLoadedInTarget(&target)) {
+          LLDB_LOGF(log,
+                    "'%s' with UUID %s is not a kmod or kernel, and is "
+                    "already registered in target, not loading.",
+                    m_name.c_str(), m_uuid.GetAsString().c_str());
+          return true;
+        }
+      }
+      m_uuid = m_module_sp->GetUUID();
+
+      // or append to the images
+      target.GetImages().AppendIfNeeded(m_module_sp, false);
+    }
+  }
+
+  // If this file is relocatable kernel module(x86_64), adjust it's
+  // section(PT_LOAD segment) and return Because the kernel module's load
+  // address is the text section. lldb cannot create full memory module upon
+  // relocatable file So what we do is to set the load address only.
+  if (is_kmod(m_module_sp.get()) && is_reloc(m_module_sp.get())) {
+    m_stop_id = process->GetStopID();
+    bool changed;
+    m_module_sp->SetLoadAddress(target, m_load_address, true, changed);
+    return true;
+  }
+
+  if (m_module_sp)
+    ReadMemoryModule(process);
+
+  // Calculate the slides of in memory module
+  if (!m_memory_module_sp || !m_module_sp) {
+    m_module_sp.reset();
+    return false;
+  }
+
+  ObjectFile *ondisk_object_file = m_module_sp->GetObjectFile();
+  ObjectFile *memory_object_file = m_memory_module_sp->GetObjectFile();
+
+  if (!ondisk_object_file || !memory_object_file)
+    m_module_sp.reset();
+
+  // Find the slide address
+  addr_t fixed_slide = LLDB_INVALID_ADDRESS;
+  if (ObjectFileELF *memory_objfile_elf =
+          llvm::dyn_cast<ObjectFileELF>(memory_object_file)) {
+    addr_t load_address = memory_object_file->GetBaseAddress().GetFileAddress();
+
+    if (load_address != LLDB_INVALID_ADDRESS &&
+        m_load_address != load_address) {
+      fixed_slide = m_load_address - load_address;
+      LLDB_LOGF(log,
+                "kmod %s in-memory LOAD vmaddr is not correct, using a "
+                "fixed slide of 0x%" PRIx64,
+                m_name.c_str(), fixed_slide);
+    }
+  }
+
+  SectionList *ondisk_section_list = ondisk_object_file->GetSectionList();
+  SectionList *memory_section_list = memory_object_file->GetSectionList();
+
+  if (memory_section_list && ondisk_object_file) {
+    const uint32_t num_ondisk_sections = ondisk_section_list->GetSize();
+    uint32_t num_load_sections = 0;
+
+    for (uint32_t section_idx = 0; section_idx < num_ondisk_sections;
+         ++section_idx) {
+      SectionSP on_disk_section_sp =
+          ondisk_section_list->GetSectionAtIndex(section_idx);
+
+      if (!on_disk_section_sp)
+        continue;
+      if (fixed_slide != LLDB_INVALID_ADDRESS) {
+        target.SetSectionLoadAddress(on_disk_section_sp,
+                                     on_disk_section_sp->GetFileAddress() +
+                                         fixed_slide);
+
+      } else {
+        const Section *memory_section =
+            memory_section_list
+                ->FindSectionByName(on_disk_section_sp->GetName())
+                .get();
+        if (memory_section) {
+          target.SetSectionLoadAddress(on_disk_section_sp,
+                                       memory_section->GetFileAddress());
+          ++num_load_sections;
+        }
+      }
+    }
+
+    if (num_load_sections)
+      m_stop_id = process->GetStopID();
+    else
+      m_module_sp.reset();
+  } else {
+    m_module_sp.reset();
+  }
+
+  if (IsLoaded() && m_module_sp && IsKernel()) {
+    Stream &s = target.GetDebugger().GetOutputStream();
+    ObjectFile *kernel_object_file = m_module_sp->GetObjectFile();
+    if (kernel_object_file) {
+      addr_t file_address =
+          kernel_object_file->GetBaseAddress().GetFileAddress();
+      if (m_load_address != LLDB_INVALID_ADDRESS &&
+          file_address != LLDB_INVALID_ADDRESS) {
+        s.Printf("Kernel slide 0x%" PRIx64 " in memory.\n",
+                 m_load_address - file_address);
+        s.Printf("Loaded kernel file %s\n",
+                 m_module_sp->GetFileSpec().GetPath().c_str());
+      }
+    }
+    s.Flush();
+  }
+
+  return IsLoaded();
+}
+
+// This function is work for kernel file, others it wil reset load address and
+// return false
+bool DynamicLoaderFreeBSDKernel::KModImageInfo::LoadImageUsingFileAddress(
+    lldb_private::Process *process) {
+  if (IsLoaded())
+    return true;
+
+  if (m_module_sp) {
+    bool changed = false;
+    if (m_module_sp->SetLoadAddress(process->GetTarget(), 0, true, changed))
+      m_stop_id = process->GetStopID();
+  }
+
+  return false;
+}
+
+// Get the head of found_list
+bool DynamicLoaderFreeBSDKernel::ReadKmodsListHeader() {
+  std::lock_guard<decltype(m_mutex)> guard(m_mutex);
+
+  if (m_linker_file_list_struct_addr.IsValid()) {
+    // Get tqh_first struct element from linker_files
+    Status error;
+    addr_t address = m_process->ReadPointerFromMemory(
+        m_linker_file_list_struct_addr.GetLoadAddress(&m_process->GetTarget()),
+        error);
+    if (address != LLDB_INVALID_ADDRESS && error.Success()) {
+      m_linker_file_head_addr = Address(address);
+    } else {
+      m_linker_file_list_struct_addr.Clear();
+      return false;
+    }
+
+    if (!m_linker_file_head_addr.IsValid() ||
+        m_linker_file_head_addr.GetFileAddress() == 0) {
+      m_linker_file_list_struct_addr.Clear();
+      return false;
+    }
+  }
+  return true;
+}
+
+// Parse Kmod info in found_list
+bool DynamicLoaderFreeBSDKernel::ParseKmods(Address linker_files_head_addr) {
+  std::lock_guard<decltype(m_mutex)> guard(m_mutex);
+  KModImageInfo::collection_type linker_files_list;
+  Log *log = GetLog(LLDBLog::DynamicLoader);
+
+  if (!ReadAllKmods(linker_files_head_addr, linker_files_list))
+    return false;
+  LLDB_LOGF(
+      log,
+      "Kmod-changed breakpoint hit, there are %lu kernel modules currently.\n",
+      linker_files_list.size());
+
+  ModuleList &modules = m_process->GetTarget().GetImages();
+  ModuleList remove_modules;
+  ModuleList add_modules;
+
+  for (ModuleSP module : modules.Modules()) {
+    if (is_kernel(module.get()))
+      continue;
+    if (is_kmod(module.get()))
+      remove_modules.AppendIfNeeded(module);
+  }
+
+  m_process->GetTarget().ModulesDidUnload(remove_modules, false);
+
+  for (KModImageInfo &image_info : linker_files_list) {
+    if (m_kld_name_to_uuid.find(image_info.GetName()) !=
+        m_kld_name_to_uuid.end())
+      image_info.SetUUID(m_kld_name_to_uuid[image_info.GetName()]);
+    bool failed_to_load = false;
+    if (!image_info.LoadImageUsingMemoryModule(m_process)) {
+      image_info.LoadImageUsingFileAddress(m_process);
+      failed_to_load = true;
+    } else {
+      m_linker_files_list.push_back(image_info);
+      m_kld_name_to_uuid[image_info.GetName()] = image_info.GetUUID();
+    }
+
+    if (!failed_to_load)
+      add_modules.AppendIfNeeded(image_info.GetModule());
+  }
+  m_process->GetTarget().ModulesDidLoad(add_modules);
+  return true;
+}
+
+// Read all kmod from a given arrays of list
+bool DynamicLoaderFreeBSDKernel::ReadAllKmods(
+    Address linker_files_head_addr,
+    KModImageInfo::collection_type &kmods_list) {
+
+  // Get offset of next member and load address symbol
+  static ConstString kld_off_address_symbol_name("kld_off_address");
+  static ConstString kld_off_next_symbol_name("kld_off_next");
+  static ConstString kld_off_filename_symbol_name("kld_off_filename");
+  static ConstString kld_off_pathname_symbol_name("kld_off_pathname");
+  const Symbol *kld_off_address_symbol =
+      m_kernel_image_info.GetModule()->FindFirstSymbolWithNameAndType(
+          kld_off_address_symbol_name, eSymbolTypeData);
+  const Symbol *kld_off_next_symbol =
+      m_kernel_image_info.GetModule()->FindFirstSymbolWithNameAndType(
+          kld_off_next_symbol_name, eSymbolTypeData);
+  const Symbol *kld_off_filename_symbol =
+      m_kernel_image_info.GetModule()->FindFirstSymbolWithNameAndType(
+          kld_off_filename_symbol_name, eSymbolTypeData);
+  const Symbol *kld_off_pathname_symbol =
+      m_kernel_image_info.GetModule()->FindFirstSymbolWithNameAndType(
+          kld_off_pathname_symbol_name, eSymbolTypeData);
+
+  if (!kld_off_address_symbol || !kld_off_next_symbol ||
+      !kld_off_filename_symbol || !kld_off_pathname_symbol)
+    return false;
+  Status error;
+  const int32_t kld_off_address = m_process->ReadSignedIntegerFromMemory(
+      kld_off_address_symbol->GetAddress().GetLoadAddress(
+          &m_process->GetTarget()),
+      4, 0, error);
+  if (error.Fail())
+    return false;
+  const int32_t kld_off_next = m_process->ReadSignedIntegerFromMemory(
+      kld_off_next_symbol->GetAddress().GetLoadAddress(&m_process->GetTarget()),
+      4, 0, error);
+  if (error.Fail())
+    return false;
+  const int32_t kld_off_filename = m_process->ReadSignedIntegerFromMemory(
+      kld_off_filename_symbol->GetAddress().GetLoadAddress(
+          &m_process->GetTarget()),
+      4, 0, error);
+  if (error.Fail())
+    return false;
+
+  const int32_t kld_off_pathname = m_process->ReadSignedIntegerFromMemory(
+      kld_off_pathname_symbol->GetAddress().GetLoadAddress(
+          &m_process->GetTarget()),
+      4, 0, error);
+  if (error.Fail())
+    return false;
+
+  // Parse KMods
+  addr_t kld_load_addr(LLDB_INVALID_ADDRESS);
+  char kld_filename[255];
+  char kld_pathname[255];
+  addr_t current_kld =
+      linker_files_head_addr.GetLoadAddress(&m_process->GetTarget());
+
+  while (current_kld != 0) {
+    m_process->ReadCStringFromMemory(
+        m_process->ReadPointerFromMemory(current_kld + kld_off_filename, error),
+        kld_filename, sizeof(kld_filename), error);
+    m_process->ReadCStringFromMemory(
+        m_process->ReadPointerFromMemory(current_kld + kld_off_pathname, error),
+        kld_pathname, sizeof(kld_pathname), error);
+    kld_load_addr =
+        m_process->ReadPointerFromMemory(current_kld + kld_off_address, error);
+
+    kmods_list.emplace_back();
+    KModImageInfo &kmod_info = kmods_list.back();
+    kmod_info.SetName(kld_filename);
+    kmod_info.SetLoadAddress(kld_load_addr);
+    kmod_info.SetPath(kld_pathname);
+    current_kld =
+        m_process->ReadPointerFromMemory(current_kld + kld_off_next, error);
----------------
bulbazord wrote:

Shouldn't you check the result of those memory reads above before mutating state here? Otherwise you may end up with stale or otherwise incorrect information, no?

https://github.com/llvm/llvm-project/pull/67106


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