From 4843c186340585eaf20610d2538f85234cc63174 Mon Sep 17 00:00:00 2001
From: Josh Gao <jmgao@google.com>
Date: Mon, 27 Aug 2018 14:52:33 -0700
Subject: [PATCH 1/2] debuggerd_handler: receive abort messages via
 sigqueue(DEBUGGER_SIGNAL).

Make it possible for code such as fdsan that generates debugging
tombstones via raise(DEBUGGER_SIGNAL) to pass an abort message as well.

Bug: http://b/112770187
Test: debuggerd_test
Change-Id: Idc34263241c18033573e466da3a45aa6f716ddb3
---
 debuggerd/handler/debuggerd_handler.cpp | 28 +++++++++++++++++--------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/debuggerd/handler/debuggerd_handler.cpp b/debuggerd/handler/debuggerd_handler.cpp
index 91e6f7111..15557b6d8 100644
--- a/debuggerd/handler/debuggerd_handler.cpp
+++ b/debuggerd/handler/debuggerd_handler.cpp
@@ -457,14 +457,14 @@ static void debuggerd_signal_handler(int signal_number, siginfo_t* info, void* c
     info = nullptr;
   }
 
-  struct siginfo si = {};
+  struct siginfo dummy_info = {};
   if (!info) {
-    memset(&si, 0, sizeof(si));
-    si.si_signo = signal_number;
-    si.si_code = SI_USER;
-    si.si_pid = __getpid();
-    si.si_uid = getuid();
-    info = &si;
+    memset(&dummy_info, 0, sizeof(dummy_info));
+    dummy_info.si_signo = signal_number;
+    dummy_info.si_code = SI_USER;
+    dummy_info.si_pid = __getpid();
+    dummy_info.si_uid = getuid();
+    info = &dummy_info;
   } else if (info->si_code >= 0 || info->si_code == SI_TKILL) {
     // rt_tgsigqueueinfo(2)'s documentation appears to be incorrect on kernels
     // that contain commit 66dd34a (3.9+). The manpage claims to only allow
@@ -473,8 +473,18 @@ static void debuggerd_signal_handler(int signal_number, siginfo_t* info, void* c
   }
 
   void* abort_message = nullptr;
-  if (signal_number != DEBUGGER_SIGNAL && g_callbacks.get_abort_message) {
-    abort_message = g_callbacks.get_abort_message();
+  if (signal_number == DEBUGGER_SIGNAL) {
+    if (info->si_code == SI_QUEUE && info->si_pid == __getpid()) {
+      // Allow for the abort message to be explicitly specified via the sigqueue value.
+      // Keep the bottom bit intact for representing whether we want a backtrace or a tombstone.
+      uintptr_t value = reinterpret_cast<uintptr_t>(info->si_ptr);
+      abort_message = reinterpret_cast<void*>(value & ~1);
+      info->si_ptr = reinterpret_cast<void*>(value & 1);
+    }
+  } else {
+    if (g_callbacks.get_abort_message) {
+      abort_message = g_callbacks.get_abort_message();
+    }
   }
 
   // If sival_int is ~0, it means that the fallback handler has been called

From bf06a40a0d8e61f2926bca9a645126fe46990051 Mon Sep 17 00:00:00 2001
From: Josh Gao <jmgao@google.com>
Date: Mon, 27 Aug 2018 16:34:01 -0700
Subject: [PATCH 2/2] debuggerd_test: add test for fdsan abort message.

Bug: http://b/112770187
Test: debuggerd_test
Test: bionic-unit-tests
Change-Id: Ia93761e89074aea4629b8d0f232c580d6f0f249c
---
 debuggerd/debuggerd_test.cpp | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/debuggerd/debuggerd_test.cpp b/debuggerd/debuggerd_test.cpp
index dfb7a6a7c..e2ea480e5 100644
--- a/debuggerd/debuggerd_test.cpp
+++ b/debuggerd/debuggerd_test.cpp
@@ -29,6 +29,7 @@
 #include <regex>
 #include <thread>
 
+#include <android/fdsan.h>
 #include <android/set_abort_message.h>
 
 #include <android-base/file.h>
@@ -801,6 +802,31 @@ TEST_F(CrasherTest, competing_tracer) {
   AssertDeath(SIGABRT);
 }
 
+TEST_F(CrasherTest, fdsan_warning_abort_message) {
+  int intercept_result;
+  unique_fd output_fd;
+
+  StartProcess([]() {
+    android_fdsan_set_error_level(ANDROID_FDSAN_ERROR_LEVEL_WARN_ONCE);
+    unique_fd fd(open("/dev/null", O_RDONLY | O_CLOEXEC));
+    if (fd == -1) {
+      abort();
+    }
+    close(fd.get());
+    _exit(0);
+  });
+
+  StartIntercept(&output_fd);
+  FinishCrasher();
+  AssertDeath(0);
+  FinishIntercept(&intercept_result);
+  ASSERT_EQ(1, intercept_result) << "tombstoned reported failure";
+
+  std::string result;
+  ConsumeFd(std::move(output_fd), &result);
+  ASSERT_MATCH(result, "Abort message: 'attempted to close");
+}
+
 TEST(crash_dump, zombie) {
   pid_t forkpid = fork();