From 86ea0741846cdab66d1bdfb5a46aaef094f5be3a Mon Sep 17 00:00:00 2001
From: Josh Gao <jmgao@google.com>
Date: Fri, 20 Apr 2018 12:04:41 -0700
Subject: [PATCH] libdebuggerd: clone registers before we Unwind with them.

Bug: http://b/77296294
Test: manual inspection of tombstone generated by crasher
Change-Id: I4b017701d7d2041db4aefbbb90977e99b844c328
(cherry picked from commit 5d1c14f41bac357c730aa47d705c1f1da7625280)
---
 debuggerd/libdebuggerd/tombstone.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/debuggerd/libdebuggerd/tombstone.cpp b/debuggerd/libdebuggerd/tombstone.cpp
index 140ef6d23..933a5972d 100644
--- a/debuggerd/libdebuggerd/tombstone.cpp
+++ b/debuggerd/libdebuggerd/tombstone.cpp
@@ -418,8 +418,10 @@ static bool dump_thread(log_t* log, BacktraceMap* map, Memory* process_memory,
 
   dump_registers(log, thread_info.registers.get());
 
+  // Unwind will mutate the registers, so make a copy first.
+  std::unique_ptr<Regs> regs_copy(thread_info.registers->Clone());
   std::vector<backtrace_frame_data_t> frames;
-  if (!Backtrace::Unwind(thread_info.registers.get(), map, &frames, 0, nullptr)) {
+  if (!Backtrace::Unwind(regs_copy.get(), map, &frames, 0, nullptr)) {
     _LOG(log, logtype::THREAD, "Failed to unwind");
     return false;
   }