Merge "Fix scudo fault address processing."

debuggerd/Android.bp

@@ -293,6 +293,13 @@ cc_test {
         "libdebuggerd/test/utility_test.cpp",
     ],
 
+    product_variables: {
+        malloc_not_svelte: {
+            srcs: ["libdebuggerd/test/scudo_test.cpp"],
+            header_libs: ["scudo_headers"],
+        },
+    },
+
     target: {
         android: {
             srcs: [

debuggerd/libdebuggerd/include/libdebuggerd/scudo.h

@@ -34,9 +34,10 @@ class Memory;
 
 class ScudoCrashData {
  public:
-  ScudoCrashData() = delete;
+  ScudoCrashData() = default;
   ~ScudoCrashData() = default;
-  ScudoCrashData(unwindstack::Memory* process_memory, const ProcessInfo& process_info);
+
+  bool SetErrorInfo(unwindstack::Memory* process_memory, const ProcessInfo& process_info);
 
   bool CrashIsMine() const;
 

debuggerd/libdebuggerd/scudo.cpp

@@ -14,6 +14,11 @@
  * limitations under the License.
  */
 
+#include <stdint.h>
+#include <unistd.h>
+
+#include <vector>
+
 #include "libdebuggerd/scudo.h"
 #include "libdebuggerd/tombstone.h"
 
@@ -25,54 +30,92 @@
 
 #include "tombstone.pb.h"
 
-std::unique_ptr<char[]> AllocAndReadFully(unwindstack::Memory* process_memory, uint64_t addr,
-                                          size_t size) {
-  auto buf = std::make_unique<char[]>(size);
-  if (!process_memory->ReadFully(addr, buf.get(), size)) {
-    return std::unique_ptr<char[]>();
-  }
-  return buf;
-}
-
-ScudoCrashData::ScudoCrashData(unwindstack::Memory* process_memory,
-                               const ProcessInfo& process_info) {
+bool ScudoCrashData::SetErrorInfo(unwindstack::Memory* process_memory,
+                                  const ProcessInfo& process_info) {
   if (!process_info.has_fault_address) {
-    return;
+    return false;
   }
 
-  auto stack_depot = AllocAndReadFully(process_memory, process_info.scudo_stack_depot,
-                                       __scudo_get_stack_depot_size());
-  auto region_info = AllocAndReadFully(process_memory, process_info.scudo_region_info,
-                                       __scudo_get_region_info_size());
-  auto ring_buffer = AllocAndReadFully(process_memory, process_info.scudo_ring_buffer,
-                                       __scudo_get_ring_buffer_size());
+  std::vector<char> stack_depot(__scudo_get_stack_depot_size());
+  if (!process_memory->ReadFully(process_info.scudo_stack_depot, stack_depot.data(),
+                                 stack_depot.size())) {
+    return false;
+  }
+  std::vector<char> region_info(__scudo_get_region_info_size());
+  if (!process_memory->ReadFully(process_info.scudo_region_info, region_info.data(),
+                                 region_info.size())) {
+    return false;
+  }
+  std::vector<char> ring_buffer(__scudo_get_ring_buffer_size());
+  if (!process_memory->ReadFully(process_info.scudo_ring_buffer, ring_buffer.data(),
+                                 ring_buffer.size())) {
+    return false;
+  }
+
+  uintptr_t page_size = getpagesize();
 
   untagged_fault_addr_ = process_info.untagged_fault_address;
-  uintptr_t fault_page = untagged_fault_addr_ & ~(PAGE_SIZE - 1);
+  uintptr_t fault_page = untagged_fault_addr_ & ~(page_size - 1);
 
-  uintptr_t memory_begin = fault_page - PAGE_SIZE * 16;
-  if (memory_begin > fault_page) {
-    return;
+  // Attempt to get 16 pages before the fault page and 16 pages after.
+  constexpr size_t kExtraPages = 16;
+  std::vector<char> memory(page_size * (kExtraPages * 2 + 1));
+
+  // Read faulting page first.
+  size_t memory_index = kExtraPages;
+  if (!process_memory->ReadFully(fault_page, &memory[memory_index * page_size], page_size)) {
+    return false;
   }
 
-  uintptr_t memory_end = fault_page + PAGE_SIZE * 16;
-  if (memory_end < fault_page) {
-    return;
+  // Attempt to read the pages after the fault page, stop as soon as we
+  // fail to read.
+  uintptr_t read_addr = fault_page;
+  if (!__builtin_add_overflow(fault_page, page_size, &read_addr)) {
+    memory_index++;
+    for (size_t i = 0; i < kExtraPages; i++, memory_index++) {
+      if (!process_memory->ReadFully(read_addr, &memory[memory_index * page_size], page_size)) {
+        break;
+      }
+      if (__builtin_add_overflow(read_addr, page_size, &read_addr)) {
+        break;
+      }
+    }
+  }
+  uintptr_t memory_end = read_addr;
+
+  // Attempt to read the pages before the fault page, stop as soon as we
+  // fail to read.
+  memory_index = kExtraPages;
+  if (fault_page > 0) {
+    read_addr = fault_page - page_size;
+    for (size_t i = 0; i < kExtraPages; i++, memory_index--) {
+      if (!process_memory->ReadFully(read_addr, &memory[(memory_index - 1) * page_size],
+                                     page_size)) {
+        break;
+      }
+      if (read_addr == 0) {
+        memory_index--;
+        break;
+      }
+      read_addr -= page_size;
+    }
+  }
+  size_t start_memory_index = memory_index;
+  uintptr_t memory_begin = fault_page - (kExtraPages - memory_index) * page_size;
+
+  std::vector<long> memory_tags((memory_end - memory_begin) / kTagGranuleSize);
+  read_addr = memory_begin;
+  for (size_t i = 0; i < memory_tags.size(); i++) {
+    memory_tags[i] = process_memory->ReadTag(read_addr);
+    read_addr += kTagGranuleSize;
   }
 
-  auto memory = std::make_unique<char[]>(memory_end - memory_begin);
-  for (auto i = memory_begin; i != memory_end; i += PAGE_SIZE) {
-    process_memory->ReadFully(i, memory.get() + i - memory_begin, PAGE_SIZE);
-  }
+  __scudo_get_error_info(
+      &error_info_, process_info.maybe_tagged_fault_address, stack_depot.data(), region_info.data(),
+      ring_buffer.data(), &memory[start_memory_index * page_size],
+      reinterpret_cast<const char*>(memory_tags.data()), memory_begin, memory_end - memory_begin);
 
-  auto memory_tags = std::make_unique<char[]>((memory_end - memory_begin) / kTagGranuleSize);
-  for (auto i = memory_begin; i != memory_end; i += kTagGranuleSize) {
-    memory_tags[(i - memory_begin) / kTagGranuleSize] = process_memory->ReadTag(i);
-  }
-
-  __scudo_get_error_info(&error_info_, process_info.maybe_tagged_fault_address, stack_depot.get(),
-                         region_info.get(), ring_buffer.get(), memory.get(), memory_tags.get(),
-                         memory_begin, memory_end - memory_begin);
+  return true;
 }
 
 bool ScudoCrashData::CrashIsMine() const {

debuggerd/libdebuggerd/test/scudo_test.cpp

@@ -0,0 +1,233 @@
+/*
+ * Copyright (C) 2022 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 <stdlib.h>
+#include <unistd.h>
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+#include "libdebuggerd/scudo.h"
+#include "libdebuggerd/types.h"
+#include "unwindstack/Memory.h"
+
+#include "log_fake.h"
+
+#include <inttypes.h>
+
+// This needs to match the kExtraPages from ScudoCrashData::SetErrorInfo.
+constexpr uint64_t kMaxPages = 16;
+
+class MemoryAlwaysZero : public unwindstack::Memory {
+ public:
+  MemoryAlwaysZero() = default;
+  virtual ~MemoryAlwaysZero() = default;
+
+  size_t Read(uint64_t addr, void* buffer, size_t size) override {
+    if (test_unreadable_addrs_.count(addr) != 0) {
+      return 0;
+    }
+    test_read_addrs_.insert(addr);
+    memset(buffer, 0, size);
+    return size;
+  }
+
+  void TestAddUnreadableAddress(uint64_t addr) { test_unreadable_addrs_.insert(addr); }
+
+  void TestClearAddresses() {
+    test_read_addrs_.clear();
+    test_unreadable_addrs_.clear();
+  }
+
+  std::set<uint64_t>& test_read_addrs() { return test_read_addrs_; }
+
+ private:
+  std::set<uint64_t> test_unreadable_addrs_;
+
+  std::set<uint64_t> test_read_addrs_;
+};
+
+TEST(ScudoTest, no_fault_address) {
+  MemoryAlwaysZero process_memory;
+  ProcessInfo info;
+  info.has_fault_address = false;
+  info.untagged_fault_address = 0x5000;
+  info.scudo_stack_depot = 0x1000;
+  info.scudo_region_info = 0x2000;
+  info.scudo_ring_buffer = 0x3000;
+
+  ScudoCrashData crash;
+  ASSERT_FALSE(crash.SetErrorInfo(&process_memory, info));
+
+  info.has_fault_address = true;
+  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
+}
+
+TEST(ScudoTest, scudo_data_read_check) {
+  MemoryAlwaysZero process_memory;
+  ProcessInfo info;
+  info.has_fault_address = true;
+  info.untagged_fault_address = 0x5000;
+  info.scudo_stack_depot = 0x1000;
+  info.scudo_region_info = 0x2000;
+  info.scudo_ring_buffer = 0x3000;
+
+  ScudoCrashData crash;
+  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
+
+  // Stack Depot unreadable
+  process_memory.TestClearAddresses();
+  process_memory.TestAddUnreadableAddress(0x1000);
+  ASSERT_FALSE(crash.SetErrorInfo(&process_memory, info));
+
+  // The Region Info doesn't exist for 32 bit.
+#if defined(__LP64__)
+  // Region Info unreadable
+  process_memory.TestClearAddresses();
+  process_memory.TestAddUnreadableAddress(0x2000);
+  ASSERT_FALSE(crash.SetErrorInfo(&process_memory, info));
+#endif
+
+  // Ring Buffer unreadable
+  process_memory.TestClearAddresses();
+  process_memory.TestAddUnreadableAddress(0x3000);
+  ASSERT_FALSE(crash.SetErrorInfo(&process_memory, info));
+
+  // Verify that with all scudo data readable, the error info works.
+  process_memory.TestClearAddresses();
+  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
+}
+
+TEST(ScudoTest, fault_page_unreadable) {
+  MemoryAlwaysZero process_memory;
+  ProcessInfo info;
+  info.has_fault_address = true;
+  info.untagged_fault_address = 0x5124;
+  info.scudo_stack_depot = 0x1000;
+  info.scudo_region_info = 0x2000;
+  info.scudo_ring_buffer = 0x3000;
+
+  ScudoCrashData crash;
+  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
+
+  uint64_t fault_page = info.untagged_fault_address & ~(getpagesize() - 1);
+  process_memory.TestAddUnreadableAddress(fault_page);
+  ASSERT_FALSE(crash.SetErrorInfo(&process_memory, info));
+}
+
+TEST(ScudoTest, pages_before_fault_unreadable) {
+  MemoryAlwaysZero process_memory;
+  ProcessInfo info;
+  info.has_fault_address = true;
+  info.untagged_fault_address = 0x15124;
+  info.scudo_stack_depot = 0x1000;
+  info.scudo_region_info = 0x2000;
+  info.scudo_ring_buffer = 0x3000;
+
+  ScudoCrashData crash;
+  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
+
+  uint64_t page_size = getpagesize();
+  uint64_t fault_page = info.untagged_fault_address & ~(page_size - 1);
+
+  std::vector<uint64_t> expected_reads = {0x1000, 0x2000, 0x3000};
+  for (size_t i = 0; i <= kMaxPages; i++) {
+    expected_reads.emplace_back(fault_page + i * page_size);
+  }
+
+  // Loop through and make pages before the fault page unreadable.
+  for (size_t i = 1; i <= kMaxPages + 1; i++) {
+    process_memory.TestClearAddresses();
+    uint64_t unreadable_addr = fault_page - i * page_size;
+    SCOPED_TRACE(testing::Message()
+                 << "Failed at unreadable address 0x" << std::hex << unreadable_addr);
+    process_memory.TestAddUnreadableAddress(unreadable_addr);
+    ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
+    ASSERT_THAT(process_memory.test_read_addrs(),
+                testing::UnorderedElementsAreArray(expected_reads));
+    // Need to add the previous unreadable_addr to the list of expected addresses.
+    expected_reads.emplace_back(unreadable_addr);
+  }
+}
+
+TEST(ScudoTest, pages_after_fault_unreadable) {
+  MemoryAlwaysZero process_memory;
+  ProcessInfo info;
+  info.has_fault_address = true;
+  info.untagged_fault_address = 0x15124;
+  info.scudo_stack_depot = 0x1000;
+  info.scudo_region_info = 0x2000;
+  info.scudo_ring_buffer = 0x3000;
+
+  ScudoCrashData crash;
+  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
+
+  uint64_t page_size = getpagesize();
+  uint64_t fault_page = info.untagged_fault_address & ~(page_size - 1);
+
+  std::vector<uint64_t> expected_reads = {0x1000, 0x2000, 0x3000};
+  for (size_t i = 0; i <= kMaxPages; i++) {
+    expected_reads.emplace_back(fault_page - i * page_size);
+  }
+
+  // Loop through and make pages after the fault page unreadable.
+  for (size_t i = 1; i <= kMaxPages + 1; i++) {
+    process_memory.TestClearAddresses();
+    uint64_t unreadable_addr = fault_page + i * page_size;
+    SCOPED_TRACE(testing::Message()
+                 << "Failed at unreadable address 0x" << std::hex << unreadable_addr);
+    process_memory.TestAddUnreadableAddress(unreadable_addr);
+    ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
+    ASSERT_THAT(process_memory.test_read_addrs(),
+                testing::UnorderedElementsAreArray(expected_reads));
+    // Need to add the previous unreadable_addr to the list of expected addresses.
+    expected_reads.emplace_back(unreadable_addr);
+  }
+}
+
+// Make sure that if the fault address is low, you won't underflow.
+TEST(ScudoTest, fault_address_low) {
+  MemoryAlwaysZero process_memory;
+  ProcessInfo info;
+  info.has_fault_address = true;
+  info.scudo_stack_depot = 0x21000;
+  info.scudo_region_info = 0x22000;
+  info.scudo_ring_buffer = 0x23000;
+
+  ScudoCrashData crash;
+  ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
+
+  uint64_t page_size = getpagesize();
+  for (size_t i = 0; i < kMaxPages + 1; i++) {
+    process_memory.TestClearAddresses();
+    info.untagged_fault_address = 0x124 + i * getpagesize();
+    SCOPED_TRACE(testing::Message()
+                 << "Failed with fault address 0x" << std::hex << info.untagged_fault_address);
+    ASSERT_TRUE(crash.SetErrorInfo(&process_memory, info));
+    std::vector<uint64_t> expected_reads = {0x21000, 0x22000, 0x23000};
+    uint64_t fault_page = info.untagged_fault_address & ~(page_size - 1);
+    expected_reads.emplace_back(fault_page);
+    for (size_t j = 1; j <= kMaxPages; j++) {
+      expected_reads.emplace_back(fault_page + j * page_size);
+    }
+    while (fault_page != 0) {
+      fault_page -= page_size;
+      expected_reads.emplace_back(fault_page);
+    }
+    ASSERT_THAT(process_memory.test_read_addrs(),
+                testing::UnorderedElementsAreArray(expected_reads));
+  }
+}

debuggerd/libdebuggerd/tombstone_proto.cpp

@@ -193,8 +193,9 @@ void set_human_readable_cause(Cause* cause, uint64_t fault_addr) {
 static void dump_probable_cause(Tombstone* tombstone, unwindstack::AndroidUnwinder* unwinder,
                                 const ProcessInfo& process_info, const ThreadInfo& main_thread) {
 #if defined(USE_SCUDO)
-  ScudoCrashData scudo_crash_data(unwinder->GetProcessMemory().get(), process_info);
-  if (scudo_crash_data.CrashIsMine()) {
+  ScudoCrashData scudo_crash_data;
+  if (scudo_crash_data.SetErrorInfo(unwinder->GetProcessMemory().get(), process_info) &&
+      scudo_crash_data.CrashIsMine()) {
     scudo_crash_data.AddCauseProtos(tombstone, unwinder);
     return;
   }