Fix fallback paths for dumping threads.

In the fallback path, if the non-main thread is the target
to be dumped, then no other threads are dumped when creating
a tombstone. Fix this and add unit tests to verify that
this all threads, including the main thread are dumped.

Bug: 234058038

Test: All unit tests pass.
Test: debuggerd -b media.swcodec process
Test: debuggerd media.swcodec process
Change-Id: Ibb75264f7b3847acdbab939a66902d986c0d0e5c

debuggerd/debuggerd_test.cpp

@@ -1486,6 +1486,37 @@ TEST_F(CrasherTest, seccomp_tombstone_thread_abort) {
   ASSERT_BACKTRACE_FRAME(result, "abort");
 }
 
+TEST_F(CrasherTest, seccomp_tombstone_multiple_threads_abort) {
+  int intercept_result;
+  unique_fd output_fd;
+
+  static const auto dump_type = kDebuggerdTombstone;
+  StartProcess(
+      []() {
+        std::thread a(foo);
+        std::thread b(bar);
+
+        std::this_thread::sleep_for(100ms);
+
+        std::thread abort_thread([] { abort(); });
+        abort_thread.join();
+      },
+      &seccomp_fork);
+
+  StartIntercept(&output_fd, dump_type);
+  FinishCrasher();
+  AssertDeath(SIGABRT);
+  FinishIntercept(&intercept_result);
+  ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
+
+  std::string result;
+  ConsumeFd(std::move(output_fd), &result);
+  ASSERT_BACKTRACE_FRAME(result, "abort");
+  ASSERT_BACKTRACE_FRAME(result, "foo");
+  ASSERT_BACKTRACE_FRAME(result, "bar");
+  ASSERT_BACKTRACE_FRAME(result, "main");
+}
+
 TEST_F(CrasherTest, seccomp_backtrace) {
   int intercept_result;
   unique_fd output_fd;
@@ -1516,6 +1547,40 @@ TEST_F(CrasherTest, seccomp_backtrace) {
   ASSERT_BACKTRACE_FRAME(result, "bar");
 }
 
+TEST_F(CrasherTest, seccomp_backtrace_from_thread) {
+  int intercept_result;
+  unique_fd output_fd;
+
+  static const auto dump_type = kDebuggerdNativeBacktrace;
+  StartProcess(
+      []() {
+        std::thread a(foo);
+        std::thread b(bar);
+
+        std::this_thread::sleep_for(100ms);
+
+        std::thread raise_thread([] {
+          raise_debugger_signal(dump_type);
+          _exit(0);
+        });
+        raise_thread.join();
+      },
+      &seccomp_fork);
+
+  StartIntercept(&output_fd, dump_type);
+  FinishCrasher();
+  AssertDeath(0);
+  FinishIntercept(&intercept_result);
+  ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
+
+  std::string result;
+  ConsumeFd(std::move(output_fd), &result);
+  ASSERT_BACKTRACE_FRAME(result, "raise_debugger_signal");
+  ASSERT_BACKTRACE_FRAME(result, "foo");
+  ASSERT_BACKTRACE_FRAME(result, "bar");
+  ASSERT_BACKTRACE_FRAME(result, "main");
+}
+
 TEST_F(CrasherTest, seccomp_crash_logcat) {
   StartProcess([]() { abort(); }, &seccomp_fork);
   FinishCrasher();

debuggerd/handler/debuggerd_fallback.cpp

@@ -210,7 +210,10 @@ static void trace_handler(siginfo_t* info, ucontext_t* ucontext) {
 
   // Send a signal to all of our siblings, asking them to dump their stack.
   pid_t current_tid = gettid();
-  if (!iterate_tids(current_tid, [&output_fd](pid_t tid) {
+  if (!iterate_tids(current_tid, [&output_fd, &current_tid](pid_t tid) {
+        if (current_tid == tid) {
+          return;
+        }
         // Use a pipe, to be able to detect situations where the thread gracefully exits before
         // receiving our signal.
         unique_fd pipe_read, pipe_write;

debuggerd/libdebuggerd/tombstone.cpp

@@ -55,15 +55,15 @@ void engrave_tombstone_ucontext(int tombstone_fd, int proto_fd, uint64_t abort_m
                                 siginfo_t* siginfo, ucontext_t* ucontext) {
   pid_t uid = getuid();
   pid_t pid = getpid();
-  pid_t tid = gettid();
+  pid_t target_tid = gettid();
 
   log_t log;
-  log.current_tid = tid;
-  log.crashed_tid = tid;
+  log.current_tid = target_tid;
+  log.crashed_tid = target_tid;
   log.tfd = tombstone_fd;
   log.amfd_data = nullptr;
 
-  std::string thread_name = get_thread_name(tid);
+  std::string thread_name = get_thread_name(target_tid);
   std::vector<std::string> command_line = get_command_line(pid);
 
   std::unique_ptr<unwindstack::Regs> regs(
@@ -73,32 +73,34 @@ void engrave_tombstone_ucontext(int tombstone_fd, int proto_fd, uint64_t abort_m
   android::base::ReadFileToString("/proc/self/attr/current", &selinux_label);
 
   std::map<pid_t, ThreadInfo> threads;
-  threads[tid] = ThreadInfo{
-    .registers = std::move(regs), .uid = uid, .tid = tid, .thread_name = std::move(thread_name),
-    .pid = pid, .command_line = std::move(command_line), .selinux_label = std::move(selinux_label),
-    .siginfo = siginfo,
+  threads[target_tid] = ThreadInfo {
+    .registers = std::move(regs), .uid = uid, .tid = target_tid,
+    .thread_name = std::move(thread_name), .pid = pid, .command_line = std::move(command_line),
+    .selinux_label = std::move(selinux_label), .siginfo = siginfo,
 #if defined(__aarch64__)
     // Only supported on aarch64 for now.
         .tagged_addr_ctrl = prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0),
     .pac_enabled_keys = prctl(PR_PAC_GET_ENABLED_KEYS, 0, 0, 0, 0),
 #endif
   };
-  if (pid == tid) {
-    const ThreadInfo& thread = threads[pid];
-    if (!iterate_tids(pid, [&threads, &thread](pid_t tid) {
-          threads[tid] = ThreadInfo{
-              .uid = thread.uid,
-              .tid = tid,
-              .pid = thread.pid,
-              .command_line = thread.command_line,
-              .thread_name = get_thread_name(tid),
-              .tagged_addr_ctrl = thread.tagged_addr_ctrl,
-              .pac_enabled_keys = thread.pac_enabled_keys,
-          };
-        })) {
-      async_safe_format_log(ANDROID_LOG_ERROR, LOG_TAG, "failed to open /proc/%d/task: %s", pid,
-                            strerror(errno));
-    }
+  const ThreadInfo& thread = threads[pid];
+  if (!iterate_tids(pid, [&threads, &thread, &target_tid](pid_t tid) {
+        if (target_tid == tid) {
+          return;
+        }
+        async_safe_format_log(ANDROID_LOG_ERROR, LOG_TAG, "Adding thread %d", tid);
+        threads[tid] = ThreadInfo{
+            .uid = thread.uid,
+            .tid = tid,
+            .pid = thread.pid,
+            .command_line = thread.command_line,
+            .thread_name = get_thread_name(tid),
+            .tagged_addr_ctrl = thread.tagged_addr_ctrl,
+            .pac_enabled_keys = thread.pac_enabled_keys,
+        };
+      })) {
+    async_safe_format_log(ANDROID_LOG_ERROR, LOG_TAG, "failed to open /proc/%d/task: %s", pid,
+                          strerror(errno));
   }
 
   // Do not use the thread cache here because it will call pthread_key_create
@@ -116,8 +118,8 @@ void engrave_tombstone_ucontext(int tombstone_fd, int proto_fd, uint64_t abort_m
 
   ProcessInfo process_info;
   process_info.abort_msg_address = abort_msg_address;
-  engrave_tombstone(unique_fd(dup(tombstone_fd)), unique_fd(dup(proto_fd)), &unwinder, threads, tid,
-                    process_info, nullptr, nullptr);
+  engrave_tombstone(unique_fd(dup(tombstone_fd)), unique_fd(dup(proto_fd)), &unwinder, threads,
+                    target_tid, process_info, nullptr, nullptr);
 }
 
 void engrave_tombstone(unique_fd output_fd, unique_fd proto_fd,

debuggerd/util.cpp

@@ -90,9 +90,7 @@ bool iterate_tids(pid_t pid, std::function<void(pid_t)> callback) {
     if (tid == 0) {
       continue;
     }
-    if (pid != tid) {
-      callback(tid);
-    }
+    callback(tid);
   }
   return true;
 }