Prevent crashes if a map cannot be created.
Under some conditions, /proc/<pid>/maps might return nothing. If we
try and unwind in this case, we'll crash. Check this case and fail
the unwind.
Add checks that no other functions try and use map_ without
checking for nullptr.
Add logging when an unwind fails so it's clear what happened.
Bug: 21162746
Change-Id: I56ce51dda0cfc9db20475a441f118108196aa07c
(cherry picked from commit 30c942cf1024bf791c28ab9b67a1f752de72248c)
diff --git a/libbacktrace/UnwindPtrace.cpp b/libbacktrace/UnwindPtrace.cpp
index a7c3de5..07c2430 100644
--- a/libbacktrace/UnwindPtrace.cpp
+++ b/libbacktrace/UnwindPtrace.cpp
@@ -48,6 +48,11 @@
}
bool UnwindPtrace::Unwind(size_t num_ignore_frames, ucontext_t* ucontext) {
+ if (GetMap() == nullptr) {
+ // Without a map object, we can't do anything.
+ return false;
+ }
+
if (ucontext) {
BACK_LOGW("Unwinding from a specified context not supported yet.");
return false;