Avoid NPE in CriticalEventLog.saveLogToFileNow()

A malformed event can cause an NPE in
CriticalEventLog.saveLogToFileNow() when
CriticalEventLogStorageProto.toByteArray() calls
computeSerializedSize() on an event with null fields. This leads to a crash system_server and will force a device reboot.

Move the toByteArray() call into the try-with-resources block
and broaden the catch from IOException to Exception so that
any exception during serialization or writing is caught and
logged rather than crashing the system_server.

Bug: None
Test: atest CriticalEventLogTest
Change-Id: I57190fc3245f9f03950f0cf7597fa3d4d2a5b550

Author: mnkassis

services/core/java/com/android/server/criticalevents/CriticalEventLog.java

@@ -397,10 +397,10 @@ protected void saveLogToFileNow() {
         CriticalEventLogStorageProto logProto = new CriticalEventLogStorageProto();
         logProto.events = mEvents.toArray();
 
-        final byte[] bytes = CriticalEventLogStorageProto.toByteArray(logProto);
         try (FileOutputStream stream = new FileOutputStream(mLogFile, false)) {
+            final byte[] bytes = CriticalEventLogStorageProto.toByteArray(logProto);
             stream.write(bytes);
-        } catch (IOException e) {
+        } catch (Exception e) {
             Slog.e(TAG, "Error saving log to disk.", e);
         }
     }

services/tests/servicestests/src/com/android/server/criticalevents/CriticalEventLogTest.java

@@ -576,6 +576,22 @@ public void saveDelayMs() {
         assertThat(mCriticalEventLog.saveDelayMs()).isEqualTo(2000L);
     }
 
+    @Test
+    public void saveLogToFileNow_withMalformedEvent_doesNotThrow() {
+        CriticalEventProto malformedEvent = new CriticalEventProto();
+        malformedEvent.timestampMs = START_TIME_MS + 1000;
+        // Set a JavaCrash with null exceptionClass - this was causing NPE in computeSerializedSize()
+        JavaCrash javaCrash = new JavaCrash();
+        javaCrash.exceptionClass = null;
+        javaCrash.process = null;
+        malformedEvent.setJavaCrash(javaCrash);
+
+        mCriticalEventLog.appendAndSave(malformedEvent);
+
+        mCriticalEventLog.saveLogToFileNow();
+        // should not throw
+    }
+
     @Test
     public void simulateReboot_saveAndLoadCycle() {
         TestableCriticalEventLog log1 = setLogInstance();