From 3cb58e571f18a6e4cdc2c299560ca2abd5958ea7 Mon Sep 17 00:00:00 2001
From: Asal Mirzaieva <asal.mirzaieva@holoplot.com>
Date: Mon, 18 May 2020 10:39:45 +0200
Subject: [PATCH] backend, logger: lock before reassigning `defaultBackend`
If not locked, this results in race:
1. SetBackend(), backend.go:26 - reassigning the global variable (write)
```
func SetBackend(backends ...Backend) LeveledBackend {
var backend Backend
// ...
// DARA RACE START
defaultBackend = AddModuleLevel(backend)
// DATA RACE END
return defaultBackend
}
```
2. IsEnabledFor(), logger.go:141 - accessing a default variable (read)
```
func (l *Logger) IsEnabledFor(level Level) bool {
return defaultBackend.IsEnabledFor(level, l.Module) // DATA RACE HERE
}
```
---
backend.go | 2 ++
level.go | 19 +++++++++++--------
logger.go | 5 ++++-
3 files changed, 17 insertions(+), 9 deletions(-)
diff --git a/backend.go b/backend.go
index 74d9201..8df5d67 100644
--- a/backend.go
+++ b/backend.go
@@ -23,7 +23,9 @@ func SetBackend(backends ...Backend) LeveledBackend {
backend = MultiLogger(backends...)
}
+ lock.Lock()
defaultBackend = AddModuleLevel(backend)
+ lock.Unlock()
return defaultBackend
}
diff --git a/level.go b/level.go
index 98dd191..b952f75 100644
--- a/level.go
+++ b/level.go
@@ -26,14 +26,17 @@ const (
DEBUG
)
-var levelNames = []string{
- "CRITICAL",
- "ERROR",
- "WARNING",
- "NOTICE",
- "INFO",
- "DEBUG",
-}
+var (
+ lock sync.Mutex
+ levelNames = []string{
+ "CRITICAL",
+ "ERROR",
+ "WARNING",
+ "NOTICE",
+ "INFO",
+ "DEBUG",
+ }
+)
// String returns the string representation of a logging level.
func (p Level) String() string {
diff --git a/logger.go b/logger.go
index 535ed9b..ce563c3 100644
--- a/logger.go
+++ b/logger.go
@@ -137,7 +137,10 @@ func Reset() {
// IsEnabledFor returns true if the logger is enabled for the given level.
func (l *Logger) IsEnabledFor(level Level) bool {
- return defaultBackend.IsEnabledFor(level, l.Module)
+ lock.Lock()
+ enabled := defaultBackend.IsEnabledFor(level, l.Module)
+ defer lock.Unlock()
+ return enabled
}
func (l *Logger) log(lvl Level, format *string, args ...interface{}) {