Merge "Prevent crashes if a map cannot be created."

debuggerd/backtrace.cpp

@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#define LOG_TAG "DEBUG"
+
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
@@ -27,6 +29,8 @@
 #include <sys/ptrace.h>
 
 #include <backtrace/Backtrace.h>
+
+#include <log/log.h>
 #include <UniquePtr.h>
 
 #include "backtrace.h"
@@ -95,6 +99,8 @@ static void dump_thread(
   UniquePtr<Backtrace> backtrace(Backtrace::Create(tid, BACKTRACE_CURRENT_THREAD));
   if (backtrace->Unwind(0)) {
     dump_backtrace_to_log(backtrace.get(), log, "  ");
+  } else {
+    ALOGE("Unwind failed: tid = %d", tid);
   }
 
   if (!attached && ptrace(PTRACE_DETACH, tid, 0, 0) != 0) {

debuggerd/tombstone.cpp

@@ -448,6 +448,8 @@ static bool dump_sibling_thread_report(
     UniquePtr<Backtrace> backtrace(Backtrace::Create(pid, new_tid, map));
     if (backtrace->Unwind(0)) {
       dump_backtrace_and_stack(backtrace.get(), log);
+    } else {
+      ALOGE("Unwind of sibling failed: pid = %d, tid = %d", pid, new_tid);
     }
 
     log->current_tid = log->crashed_tid;
@@ -650,9 +652,13 @@ static bool dump_crash(log_t* log, pid_t pid, pid_t tid, int signal, int si_code
   dump_registers(log, tid);
   if (backtrace->Unwind(0)) {
     dump_backtrace_and_stack(backtrace.get(), log);
+  } else {
+    ALOGE("Unwind failed: pid = %d, tid = %d", pid, tid);
   }
   dump_memory_and_code(log, tid);
-  dump_all_maps(backtrace.get(), map.get(), log, tid);
+  if (map.get() != nullptr) {
+    dump_all_maps(backtrace.get(), map.get(), log, tid);
+  }
 
   if (want_logs) {
     dump_logs(log, pid, 5);

libbacktrace/Backtrace.cpp

@@ -114,7 +114,9 @@ std::string Backtrace::FormatFrameData(const backtrace_frame_data_t* frame) {
 }
 
 void Backtrace::FillInMap(uintptr_t pc, backtrace_map_t* map) {
-  map_->FillIn(pc, map);
+  if (map_ != nullptr) {
+    map_->FillIn(pc, map);
+  }
 }
 
 Backtrace* Backtrace::Create(pid_t pid, pid_t tid, BacktraceMap* map) {

libbacktrace/BacktraceCurrent.cpp

@@ -65,6 +65,11 @@ size_t BacktraceCurrent::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
 }
 
 bool BacktraceCurrent::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
+  if (GetMap() == nullptr) {
+    // Without a map object, we can't do anything.
+    return false;
+  }
+
   if (ucontext) {
     return UnwindFromContext(num_ignore_frames, ucontext);
   }

libbacktrace/UnwindPtrace.cpp

@@ -48,6 +48,11 @@ UnwindPtrace::~UnwindPtrace() {
 }
 
 bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
+  if (GetMap() == nullptr) {
+    // Without a map object, we can't do anything.
+    return false;
+  }
+
   if (ucontext) {
     BACK_LOGW("Unwinding from a specified context not supported yet.");
     return false;