debuggerd/libdebuggerd/gwp_asan.cpp - platform/system/core - Git at Google

 /*
  * Copyright (C) 2020 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include "libdebuggerd/gwp_asan.h"
 #include "libdebuggerd/utility.h"

 #include "gwp_asan/common.h"
 #include "gwp_asan/crash_handler.h"

 #include <unwindstack/Maps.h>
 #include <unwindstack/Memory.h>
 #include <unwindstack/Regs.h>
 #include <unwindstack/Unwinder.h>

 // Retrieve GWP-ASan state from `state_addr` inside the process at
 // `process_memory`. Place the state into `*state`.
 static bool retrieve_gwp_asan_state(unwindstack::Memory* process_memory, uintptr_t state_addr,
                                     gwp_asan::AllocatorState* state) {
   return process_memory->ReadFully(state_addr, state, sizeof(*state));
 }

 // Retrieve the GWP-ASan metadata pool from `metadata_addr` inside the process
 // at `process_memory`. The number of metadata slots is retrieved from the
 // allocator state provided. This function returns a heap-allocated copy of the
 // metadata pool whose ownership should be managed by the caller. Returns
 // nullptr on failure.
 static const gwp_asan::AllocationMetadata* retrieve_gwp_asan_metadata(
     unwindstack::Memory* process_memory, const gwp_asan::AllocatorState& state,
     uintptr_t metadata_addr) {
   if (state.MaxSimultaneousAllocations > 1024) {
     ALOGE(
         "Error when retrieving GWP-ASan metadata, MSA from state (%zu) "
         "exceeds maximum allowed (1024).",
         state.MaxSimultaneousAllocations);
     return nullptr;
   }

   gwp_asan::AllocationMetadata* meta =
       new gwp_asan::AllocationMetadata[state.MaxSimultaneousAllocations];
   if (!process_memory->ReadFully(metadata_addr, meta,
                                  sizeof(*meta) * state.MaxSimultaneousAllocations)) {
     ALOGE(
         "Error when retrieving GWP-ASan metadata, could not retrieve %zu "
         "pieces of metadata.",
         state.MaxSimultaneousAllocations);
     delete[] meta;
     meta = nullptr;
   }
   return meta;
 }

 GwpAsanCrashData::GwpAsanCrashData(unwindstack::Memory* process_memory,
                                    uintptr_t gwp_asan_state_ptr, uintptr_t gwp_asan_metadata_ptr,
                                    const ThreadInfo& thread_info) {
   if (!process_memory || !gwp_asan_metadata_ptr || !gwp_asan_state_ptr) return;
   // Extract the GWP-ASan regions from the dead process.
   if (!retrieve_gwp_asan_state(process_memory, gwp_asan_state_ptr, &state_)) return;
   metadata_.reset(retrieve_gwp_asan_metadata(process_memory, state_, gwp_asan_metadata_ptr));
   if (!metadata_.get()) return;

   // Get the external crash address from the thread info.
   crash_address_ = 0u;
   if (signal_has_si_addr(thread_info.siginfo)) {
     crash_address_ = reinterpret_cast<uintptr_t>(thread_info.siginfo->si_addr);
   }

   // Ensure the error belongs to GWP-ASan.
   if (!__gwp_asan_error_is_mine(&state_, crash_address_)) return;

   is_gwp_asan_responsible_ = true;
   thread_id_ = thread_info.tid;

   // Grab the internal error address, if it exists.
   uintptr_t internal_crash_address = __gwp_asan_get_internal_crash_address(&state_);
   if (internal_crash_address) {
     crash_address_ = internal_crash_address;
   }

   // Get other information from the internal state.
   error_ = __gwp_asan_diagnose_error(&state_, metadata_.get(), crash_address_);
   error_string_ = gwp_asan::ErrorToString(error_);
   responsible_allocation_ = __gwp_asan_get_metadata(&state_, metadata_.get(), crash_address_);
 }

 bool GwpAsanCrashData::CrashIsMine() const {
   return is_gwp_asan_responsible_;
 }

 void GwpAsanCrashData::DumpCause(log_t* log) const {
   if (!CrashIsMine()) {
     ALOGE("Internal Error: DumpCause() on a non-GWP-ASan crash.");
     return;
   }

   if (error_ == gwp_asan::Error::UNKNOWN) {
     _LOG(log, logtype::HEADER, "Cause: [GWP-ASan]: Unknown error occurred at 0x%" PRIxPTR ".\n",
          crash_address_);
     return;
   }

   if (!responsible_allocation_) {
     _LOG(log, logtype::HEADER, "Cause: [GWP-ASan]: %s at 0x%" PRIxPTR ".\n", error_string_,
          crash_address_);
     return;
   }

   uintptr_t alloc_address = __gwp_asan_get_allocation_address(responsible_allocation_);
   size_t alloc_size = __gwp_asan_get_allocation_size(responsible_allocation_);

   if (crash_address_ == alloc_address) {
     // Use After Free on a 41-byte allocation at 0xdeadbeef.
     _LOG(log, logtype::HEADER, "Cause: [GWP-ASan]: %s on a %zu-byte allocation at 0x%" PRIxPTR "\n",
          error_string_, alloc_size, alloc_address);
     return;
   }

   uintptr_t diff;
   const char* location_str;

   if (crash_address_ < alloc_address) {
     // Buffer Underflow, 6 bytes left of a 41-byte allocation at 0xdeadbeef.
     location_str = "left of";
     diff = alloc_address - crash_address_;
   } else if (crash_address_ - alloc_address < alloc_size) {
     // Use After Free, 40 bytes into a 41-byte allocation at 0xdeadbeef.
     location_str = "into";
     diff = crash_address_ - alloc_address;
   } else {
     // Buffer Overflow, 6 bytes right of a 41-byte allocation at 0xdeadbeef, or
     // Invalid Free, 47 bytes right of a 41-byte allocation at 0xdeadbeef.
     location_str = "right of";
     diff = crash_address_ - alloc_address;
     if (error_ == gwp_asan::Error::BUFFER_OVERFLOW) {
       diff -= alloc_size;
     }
   }

   // Suffix of 'bytes', i.e. 4 bytes' vs. '1 byte'.
   const char* byte_suffix = "s";
   if (diff == 1) {
     byte_suffix = "";
   }
   _LOG(log, logtype::HEADER,
        "Cause: [GWP-ASan]: %s, %" PRIuPTR " byte%s %s a %zu-byte allocation at 0x%" PRIxPTR "\n",
        error_string_, diff, byte_suffix, location_str, alloc_size, alloc_address);
 }

 // Build a frame for symbolization using the maps from the provided unwinder.
 // The constructed frame contains just enough information to be used to
 // symbolize a GWP-ASan stack trace.
 static unwindstack::FrameData BuildFrame(unwindstack::Unwinder* unwinder, uintptr_t pc,
                                          size_t frame_num) {
   unwindstack::FrameData frame;
   frame.num = frame_num;

   unwindstack::Maps* maps = unwinder->GetMaps();
   unwindstack::MapInfo* map_info = maps->Find(pc);
   if (!map_info) {
     frame.rel_pc = pc;
     return frame;
   }

   unwindstack::Elf* elf =
       map_info->GetElf(unwinder->GetProcessMemory(), unwindstack::Regs::CurrentArch());

   uint64_t relative_pc = elf->GetRelPc(pc, map_info);

   // Create registers just to get PC adjustment. Doesn't matter what they point
   // to.
   unwindstack::Regs* regs = unwindstack::Regs::CreateFromLocal();
   uint64_t pc_adjustment = regs->GetPcAdjustment(relative_pc, elf);
   relative_pc -= pc_adjustment;
   // The debug PC may be different if the PC comes from the JIT.
   uint64_t debug_pc = relative_pc;

   // If we don't have a valid ELF file, check the JIT.
   if (!elf->valid()) {
     unwindstack::JitDebug jit_debug(unwinder->GetProcessMemory());
     uint64_t jit_pc = pc - pc_adjustment;
     unwindstack::Elf* jit_elf = jit_debug.GetElf(maps, jit_pc);
     if (jit_elf != nullptr) {
       debug_pc = jit_pc;
       elf = jit_elf;
     }
   }

   // Copy all the things we need into the frame for symbolization.
   frame.rel_pc = relative_pc;
   frame.pc = pc - pc_adjustment;
   frame.map_name = map_info->name;
   frame.map_elf_start_offset = map_info->elf_start_offset;
   frame.map_exact_offset = map_info->offset;
   frame.map_start = map_info->start;
   frame.map_end = map_info->end;
   frame.map_flags = map_info->flags;
   frame.map_load_bias = elf->GetLoadBias();

   if (!elf->GetFunctionName(relative_pc, &frame.function_name, &frame.function_offset)) {
     frame.function_name = "";
     frame.function_offset = 0;
   }
   return frame;
 }

 constexpr size_t kMaxTraceLength = gwp_asan::AllocationMetadata::kMaxTraceLengthToCollect;

 bool GwpAsanCrashData::HasDeallocationTrace() const {
   assert(CrashIsMine() && "HasDeallocationTrace(): Crash is not mine!");
   if (!responsible_allocation_ || !__gwp_asan_is_deallocated(responsible_allocation_)) {
     return false;
   }
   return true;
 }

 void GwpAsanCrashData::DumpDeallocationTrace(log_t* log, unwindstack::Unwinder* unwinder) const {
   assert(HasDeallocationTrace() && "DumpDeallocationTrace(): No dealloc trace!");
   uint64_t thread_id = __gwp_asan_get_deallocation_thread_id(responsible_allocation_);

   std::unique_ptr<uintptr_t> frames(new uintptr_t[kMaxTraceLength]);
   size_t num_frames =
       __gwp_asan_get_deallocation_trace(responsible_allocation_, frames.get(), kMaxTraceLength);

   if (thread_id == gwp_asan::kInvalidThreadID) {
     _LOG(log, logtype::BACKTRACE, "\ndeallocated by thread <unknown>:\n");
   } else {
     _LOG(log, logtype::BACKTRACE, "\ndeallocated by thread %" PRIu64 ":\n", thread_id);
   }

   unwinder->SetDisplayBuildID(true);
   for (size_t i = 0; i < num_frames; ++i) {
     unwindstack::FrameData frame_data = BuildFrame(unwinder, frames.get()[i], i);
     _LOG(log, logtype::BACKTRACE, "    %s\n", unwinder->FormatFrame(frame_data).c_str());
   }
 }

 bool GwpAsanCrashData::HasAllocationTrace() const {
   assert(CrashIsMine() && "HasAllocationTrace(): Crash is not mine!");
   return responsible_allocation_ != nullptr;
 }

 void GwpAsanCrashData::DumpAllocationTrace(log_t* log, unwindstack::Unwinder* unwinder) const {
   assert(HasAllocationTrace() && "DumpAllocationTrace(): No dealloc trace!");
   uint64_t thread_id = __gwp_asan_get_allocation_thread_id(responsible_allocation_);

   std::unique_ptr<uintptr_t> frames(new uintptr_t[kMaxTraceLength]);
   size_t num_frames =
       __gwp_asan_get_allocation_trace(responsible_allocation_, frames.get(), kMaxTraceLength);

   if (thread_id == gwp_asan::kInvalidThreadID) {
     _LOG(log, logtype::BACKTRACE, "\nallocated by thread <unknown>:\n");
   } else {
     _LOG(log, logtype::BACKTRACE, "\nallocated by thread %" PRIu64 ":\n", thread_id);
   }

   unwinder->SetDisplayBuildID(true);
   for (size_t i = 0; i < num_frames; ++i) {
     unwindstack::FrameData frame_data = BuildFrame(unwinder, frames.get()[i], i);
     _LOG(log, logtype::BACKTRACE, "    %s\n", unwinder->FormatFrame(frame_data).c_str());
   }
 }
	/*
	* Copyright (C) 2020 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include "libdebuggerd/gwp_asan.h"
	#include "libdebuggerd/utility.h"

	#include "gwp_asan/common.h"
	#include "gwp_asan/crash_handler.h"

	#include <unwindstack/Maps.h>
	#include <unwindstack/Memory.h>
	#include <unwindstack/Regs.h>
	#include <unwindstack/Unwinder.h>

	// Retrieve GWP-ASan state from `state_addr` inside the process at
	// `process_memory`. Place the state into `*state`.
	static bool retrieve_gwp_asan_state(unwindstack::Memory* process_memory, uintptr_t state_addr,
	gwp_asan::AllocatorState* state) {
	return process_memory->ReadFully(state_addr, state, sizeof(*state));
	}

	// Retrieve the GWP-ASan metadata pool from `metadata_addr` inside the process
	// at `process_memory`. The number of metadata slots is retrieved from the
	// allocator state provided. This function returns a heap-allocated copy of the
	// metadata pool whose ownership should be managed by the caller. Returns
	// nullptr on failure.
	static const gwp_asan::AllocationMetadata* retrieve_gwp_asan_metadata(
	unwindstack::Memory* process_memory, const gwp_asan::AllocatorState& state,
	uintptr_t metadata_addr) {
	if (state.MaxSimultaneousAllocations > 1024) {
	ALOGE(
	"Error when retrieving GWP-ASan metadata, MSA from state (%zu) "
	"exceeds maximum allowed (1024).",
	state.MaxSimultaneousAllocations);
	return nullptr;
	}

	gwp_asan::AllocationMetadata* meta =
	new gwp_asan::AllocationMetadata[state.MaxSimultaneousAllocations];
	if (!process_memory->ReadFully(metadata_addr, meta,
	sizeof(meta) state.MaxSimultaneousAllocations)) {
	ALOGE(
	"Error when retrieving GWP-ASan metadata, could not retrieve %zu "
	"pieces of metadata.",
	state.MaxSimultaneousAllocations);
	delete[] meta;
	meta = nullptr;
	}
	return meta;
	}

	GwpAsanCrashData::GwpAsanCrashData(unwindstack::Memory* process_memory,
	uintptr_t gwp_asan_state_ptr, uintptr_t gwp_asan_metadata_ptr,
	const ThreadInfo& thread_info) {
	if (!process_memory \|\| !gwp_asan_metadata_ptr \|\| !gwp_asan_state_ptr) return;
	// Extract the GWP-ASan regions from the dead process.
	if (!retrieve_gwp_asan_state(process_memory, gwp_asan_state_ptr, &state_)) return;
	metadata_.reset(retrieve_gwp_asan_metadata(process_memory, state_, gwp_asan_metadata_ptr));
	if (!metadata_.get()) return;

	// Get the external crash address from the thread info.
	crash_address_ = 0u;
	if (signal_has_si_addr(thread_info.siginfo)) {
	crash_address_ = reinterpret_cast<uintptr_t>(thread_info.siginfo->si_addr);
	}

	// Ensure the error belongs to GWP-ASan.
	if (!__gwp_asan_error_is_mine(&state_, crash_address_)) return;

	is_gwp_asan_responsible_ = true;
	thread_id_ = thread_info.tid;

	// Grab the internal error address, if it exists.
	uintptr_t internal_crash_address = __gwp_asan_get_internal_crash_address(&state_);
	if (internal_crash_address) {
	crash_address_ = internal_crash_address;
	}

	// Get other information from the internal state.
	error_ = __gwp_asan_diagnose_error(&state_, metadata_.get(), crash_address_);
	error_string_ = gwp_asan::ErrorToString(error_);
	responsible_allocation_ = __gwp_asan_get_metadata(&state_, metadata_.get(), crash_address_);
	}

	bool GwpAsanCrashData::CrashIsMine() const {
	return is_gwp_asan_responsible_;
	}

	void GwpAsanCrashData::DumpCause(log_t* log) const {
	if (!CrashIsMine()) {
	ALOGE("Internal Error: DumpCause() on a non-GWP-ASan crash.");
	return;
	}

	if (error_ == gwp_asan::Error::UNKNOWN) {
	_LOG(log, logtype::HEADER, "Cause: [GWP-ASan]: Unknown error occurred at 0x%" PRIxPTR ".\n",
	crash_address_);
	return;
	}

	if (!responsible_allocation_) {
	_LOG(log, logtype::HEADER, "Cause: [GWP-ASan]: %s at 0x%" PRIxPTR ".\n", error_string_,
	crash_address_);
	return;
	}

	uintptr_t alloc_address = __gwp_asan_get_allocation_address(responsible_allocation_);
	size_t alloc_size = __gwp_asan_get_allocation_size(responsible_allocation_);

	if (crash_address_ == alloc_address) {
	// Use After Free on a 41-byte allocation at 0xdeadbeef.
	_LOG(log, logtype::HEADER, "Cause: [GWP-ASan]: %s on a %zu-byte allocation at 0x%" PRIxPTR "\n",
	error_string_, alloc_size, alloc_address);
	return;
	}

	uintptr_t diff;
	const char* location_str;

	if (crash_address_ < alloc_address) {
	// Buffer Underflow, 6 bytes left of a 41-byte allocation at 0xdeadbeef.
	location_str = "left of";
	diff = alloc_address - crash_address_;
	} else if (crash_address_ - alloc_address < alloc_size) {
	// Use After Free, 40 bytes into a 41-byte allocation at 0xdeadbeef.
	location_str = "into";
	diff = crash_address_ - alloc_address;
	} else {
	// Buffer Overflow, 6 bytes right of a 41-byte allocation at 0xdeadbeef, or
	// Invalid Free, 47 bytes right of a 41-byte allocation at 0xdeadbeef.
	location_str = "right of";
	diff = crash_address_ - alloc_address;
	if (error_ == gwp_asan::Error::BUFFER_OVERFLOW) {
	diff -= alloc_size;
	}
	}

	// Suffix of 'bytes', i.e. 4 bytes' vs. '1 byte'.
	const char* byte_suffix = "s";
	if (diff == 1) {
	byte_suffix = "";
	}
	_LOG(log, logtype::HEADER,
	"Cause: [GWP-ASan]: %s, %" PRIuPTR " byte%s %s a %zu-byte allocation at 0x%" PRIxPTR "\n",
	error_string_, diff, byte_suffix, location_str, alloc_size, alloc_address);
	}

	// Build a frame for symbolization using the maps from the provided unwinder.
	// The constructed frame contains just enough information to be used to
	// symbolize a GWP-ASan stack trace.
	static unwindstack::FrameData BuildFrame(unwindstack::Unwinder* unwinder, uintptr_t pc,
	size_t frame_num) {
	unwindstack::FrameData frame;
	frame.num = frame_num;

	unwindstack::Maps* maps = unwinder->GetMaps();
	unwindstack::MapInfo* map_info = maps->Find(pc);
	if (!map_info) {
	frame.rel_pc = pc;
	return frame;
	}

	unwindstack::Elf* elf =
	map_info->GetElf(unwinder->GetProcessMemory(), unwindstack::Regs::CurrentArch());

	uint64_t relative_pc = elf->GetRelPc(pc, map_info);

	// Create registers just to get PC adjustment. Doesn't matter what they point
	// to.
	unwindstack::Regs* regs = unwindstack::Regs::CreateFromLocal();
	uint64_t pc_adjustment = regs->GetPcAdjustment(relative_pc, elf);
	relative_pc -= pc_adjustment;
	// The debug PC may be different if the PC comes from the JIT.
	uint64_t debug_pc = relative_pc;

	// If we don't have a valid ELF file, check the JIT.
	if (!elf->valid()) {
	unwindstack::JitDebug jit_debug(unwinder->GetProcessMemory());
	uint64_t jit_pc = pc - pc_adjustment;
	unwindstack::Elf* jit_elf = jit_debug.GetElf(maps, jit_pc);
	if (jit_elf != nullptr) {
	debug_pc = jit_pc;
	elf = jit_elf;
	}
	}

	// Copy all the things we need into the frame for symbolization.
	frame.rel_pc = relative_pc;
	frame.pc = pc - pc_adjustment;
	frame.map_name = map_info->name;
	frame.map_elf_start_offset = map_info->elf_start_offset;
	frame.map_exact_offset = map_info->offset;
	frame.map_start = map_info->start;
	frame.map_end = map_info->end;
	frame.map_flags = map_info->flags;
	frame.map_load_bias = elf->GetLoadBias();

	if (!elf->GetFunctionName(relative_pc, &frame.function_name, &frame.function_offset)) {
	frame.function_name = "";
	frame.function_offset = 0;
	}
	return frame;
	}

	constexpr size_t kMaxTraceLength = gwp_asan::AllocationMetadata::kMaxTraceLengthToCollect;

	bool GwpAsanCrashData::HasDeallocationTrace() const {
	assert(CrashIsMine() && "HasDeallocationTrace(): Crash is not mine!");
	if (!responsible_allocation_ \|\| !__gwp_asan_is_deallocated(responsible_allocation_)) {
	return false;
	}
	return true;
	}

	void GwpAsanCrashData::DumpDeallocationTrace(log_t* log, unwindstack::Unwinder* unwinder) const {
	assert(HasDeallocationTrace() && "DumpDeallocationTrace(): No dealloc trace!");
	uint64_t thread_id = __gwp_asan_get_deallocation_thread_id(responsible_allocation_);

	std::unique_ptr<uintptr_t> frames(new uintptr_t[kMaxTraceLength]);
	size_t num_frames =
	__gwp_asan_get_deallocation_trace(responsible_allocation_, frames.get(), kMaxTraceLength);

	if (thread_id == gwp_asan::kInvalidThreadID) {
	_LOG(log, logtype::BACKTRACE, "\ndeallocated by thread <unknown>:\n");
	} else {
	_LOG(log, logtype::BACKTRACE, "\ndeallocated by thread %" PRIu64 ":\n", thread_id);
	}

	unwinder->SetDisplayBuildID(true);
	for (size_t i = 0; i < num_frames; ++i) {
	unwindstack::FrameData frame_data = BuildFrame(unwinder, frames.get()[i], i);
	_LOG(log, logtype::BACKTRACE, " %s\n", unwinder->FormatFrame(frame_data).c_str());
	}
	}

	bool GwpAsanCrashData::HasAllocationTrace() const {
	assert(CrashIsMine() && "HasAllocationTrace(): Crash is not mine!");
	return responsible_allocation_ != nullptr;
	}

	void GwpAsanCrashData::DumpAllocationTrace(log_t* log, unwindstack::Unwinder* unwinder) const {
	assert(HasAllocationTrace() && "DumpAllocationTrace(): No dealloc trace!");
	uint64_t thread_id = __gwp_asan_get_allocation_thread_id(responsible_allocation_);

	std::unique_ptr<uintptr_t> frames(new uintptr_t[kMaxTraceLength]);
	size_t num_frames =
	__gwp_asan_get_allocation_trace(responsible_allocation_, frames.get(), kMaxTraceLength);

	if (thread_id == gwp_asan::kInvalidThreadID) {
	_LOG(log, logtype::BACKTRACE, "\nallocated by thread <unknown>:\n");
	} else {
	_LOG(log, logtype::BACKTRACE, "\nallocated by thread %" PRIu64 ":\n", thread_id);
	}

	unwinder->SetDisplayBuildID(true);
	for (size_t i = 0; i < num_frames; ++i) {
	unwindstack::FrameData frame_data = BuildFrame(unwinder, frames.get()[i], i);
	_LOG(log, logtype::BACKTRACE, " %s\n", unwinder->FormatFrame(frame_data).c_str());
	}
	}