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
diff --git a/debuggerd/backtrace.cpp b/debuggerd/backtrace.cpp
index c2a1dbc..79ee4e5 100644
--- a/debuggerd/backtrace.cpp
+++ b/debuggerd/backtrace.cpp
@@ -14,6 +14,8 @@
* limitations under the License.
*/
+#define LOG_TAG "DEBUG"
+
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
@@ -27,6 +29,8 @@
#include <sys/ptrace.h>
#include <backtrace/Backtrace.h>
+
+#include <log/log.h>
#include <UniquePtr.h>
#include "backtrace.h"
@@ -95,6 +99,8 @@
UniquePtr<Backtrace> backtrace(Backtrace::Create(tid, BACKTRACE_CURRENT_THREAD));
if (backtrace->Unwind(0)) {
dump_backtrace_to_log(backtrace.get(), log, " ");
+ } else {
+ ALOGE("Unwind failed: tid = %d", tid);
}
if (!attached && ptrace(PTRACE_DETACH, tid, 0, 0) != 0) {