commit 70d8f289454c9b691ec5421b0ed0354b6baaace8
author Elliott Hughes <enh@google.com> Wed Apr 25 17:00:14 2018 -0700
committer Elliott Hughes <enh@google.com> Thu Apr 26 08:19:17 2018 -0700
tree 065570ea913e9c631e13807522fa0361e5c26e5e
parent f88905d231367eeeb72379d9eb2debbadb47b788

Show signal sender for SI_FROMUSER signals.

Suicide doesn't change:

  signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr --------

But homicide now looks like this (this is `sleep 666` killed by
`kill -SEGV` as root:

  signal 11 (SIGSEGV), code 0 (SI_USER from pid 4446, uid 0), fault addr --------

Bug: http://b/78594105
Test: manual
Change-Id: I8c2feafba8cc5a3db85e8250004d428a464c5d9e

debuggerd/libdebuggerd/tombstone.cpp

diff --git a/debuggerd/libdebuggerd/tombstone.cpp b/debuggerd/libdebuggerd/tombstone.cpp
index af8072e..e11be1e 100644
--- a/debuggerd/libdebuggerd/tombstone.cpp
+++ b/debuggerd/libdebuggerd/tombstone.cpp
@@ -102,18 +102,24 @@
   if (!cause.empty()) _LOG(log, logtype::HEADER, "Cause: %s\n", cause.c_str());
 }
 
-static void dump_signal_info(log_t* log, const siginfo_t* si) {
+static void dump_signal_info(log_t* log, const ThreadInfo& thread_info) {
   char addr_desc[32]; // ", fault addr 0x1234"
-  if (signal_has_si_addr(si->si_signo, si->si_code)) {
-    snprintf(addr_desc, sizeof(addr_desc), "%p", si->si_addr);
+  if (signal_has_si_addr(thread_info.siginfo)) {
+    snprintf(addr_desc, sizeof(addr_desc), "%p", thread_info.siginfo->si_addr);
   } else {
     snprintf(addr_desc, sizeof(addr_desc), "--------");
   }
 
-  _LOG(log, logtype::HEADER, "signal %d (%s), code %d (%s), fault addr %s\n", si->si_signo,
-       get_signame(si->si_signo), si->si_code, get_sigcode(si->si_signo, si->si_code), addr_desc);
+  char sender_desc[32] = {};  // " from pid 1234, uid 666"
+  if (signal_has_sender(thread_info.siginfo, thread_info.pid)) {
+    get_signal_sender(sender_desc, sizeof(sender_desc), thread_info.siginfo);
+  }
 
-  dump_probable_cause(log, si);
+  _LOG(log, logtype::HEADER, "signal %d (%s), code %d (%s%s), fault addr %s\n",
+       thread_info.siginfo->si_signo, get_signame(thread_info.siginfo),
+       thread_info.siginfo->si_code, get_sigcode(thread_info.siginfo), sender_desc, addr_desc);
+
+  dump_probable_cause(log, thread_info.siginfo);
 }
 
 static void dump_thread_info(log_t* log, const ThreadInfo& thread_info) {
@@ -412,7 +418,7 @@
   dump_thread_info(log, thread_info);
 
   if (thread_info.siginfo) {
-    dump_signal_info(log, thread_info.siginfo);
+    dump_signal_info(log, thread_info);
   }
 
   if (primary_thread) {
@@ -442,7 +448,7 @@
     if (map) {
       uint64_t addr = 0;
       siginfo_t* si = thread_info.siginfo;
-      if (signal_has_si_addr(si->si_signo, si->si_code)) {
+      if (signal_has_si_addr(si)) {
         addr = reinterpret_cast<uint64_t>(si->si_addr);
       }
       dump_all_maps(log, map, process_memory, addr);