libdebuggerd: clone registers before we Unwind with them.

Bug: http://b/77296294
Test: manual inspection of tombstone generated by crasher
Change-Id: I4b017701d7d2041db4aefbbb90977e99b844c328

1 files changed, 3 insertions, 1 deletions

diff --git a/debuggerd/libdebuggerd/tombstone.cpp b/debuggerd/libdebuggerd/tombstone.cpp
index 55d6204ac..2b7529217 100644
--- a/debuggerd/libdebuggerd/tombstone.cpp
+++ b/debuggerd/libdebuggerd/tombstone.cpp
@@ -422,8 +422,10 @@ 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;
   }