From f9a4bb18ffa1605cced3ee4b161675a0c88941be Mon Sep 17 00:00:00 2001
From: Tej Singh <singhtejinder@google.com>
Date: Thu, 10 Sep 2020 23:20:58 -0700
Subject: [PATCH] Fix thread safety issue on clearing cache

Historically, we havent held a lock on ForceClearCache and
ClearCacheIfNecessary. This is not thread safe because kAllPullAtomInfo
must be accessed in a lock, especially now that pullers can be
registered/unregistered.

Test: atest statsd_test, wrote a repro cl.
Bug: 168156854
Change-Id: I47d53a6d9d274bca4c78dbfd87e0097091b7b8cb
---
 cmds/statsd/src/external/StatsPullerManager.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/cmds/statsd/src/external/StatsPullerManager.cpp b/cmds/statsd/src/external/StatsPullerManager.cpp
index 46c377037542a..8334b6b4db908 100644
--- a/cmds/statsd/src/external/StatsPullerManager.cpp
+++ b/cmds/statsd/src/external/StatsPullerManager.cpp
@@ -315,6 +315,7 @@ void StatsPullerManager::OnAlarmFired(int64_t elapsedTimeNs) {
 }
 
 int StatsPullerManager::ForceClearPullerCache() {
+    std::lock_guard<std::mutex> _l(mLock);
     int totalCleared = 0;
     for (const auto& pulledAtom : kAllPullAtomInfo) {
         totalCleared += pulledAtom.second->ForceClearCache();
@@ -323,6 +324,7 @@ int StatsPullerManager::ForceClearPullerCache() {
 }
 
 int StatsPullerManager::ClearPullerCacheIfNecessary(int64_t timestampNs) {
+    std::lock_guard<std::mutex> _l(mLock);
     int totalCleared = 0;
     for (const auto& pulledAtom : kAllPullAtomInfo) {
         totalCleared += pulledAtom.second->ClearCacheIfNecessary(timestampNs);