diff --git a/HISTORY b/HISTORY
index 2242786..40a12a0 100644
--- a/HISTORY
+++ b/HISTORY
@@ -1,4 +1,7 @@
 
+Version 1.12  2014-12-05
+  * bug fixed: must check the return value of vsnprintf
+
 Version 1.11  2014-11-20
   * remove usleep call in logger.c
   * bug fixed: NOT set last_block->next when realloc
diff --git a/libfastcommon.spec b/libfastcommon.spec
index 8b25f71..56bce2e 100644
--- a/libfastcommon.spec
+++ b/libfastcommon.spec
@@ -1,5 +1,5 @@
 Name: libfastcommon
-Version: 1.0.11
+Version: 1.0.12
 Release: 1%{?dist}
 Summary: c common functions library extracted from my open source projects FastDFS
 License: GPL
diff --git a/src/logger.c b/src/logger.c
index 2d1a977..9bc89c3 100644
--- a/src/logger.c
+++ b/src/logger.c
@@ -800,6 +800,10 @@ void log_it_ex(LogContext *pContext, const int priority, const char *format, ...
 	va_start(ap, format);
 	len = vsnprintf(text, sizeof(text), format, ap);
 	va_end(ap);
+    if (len > sizeof(text))
+    {
+        len = sizeof(text);
+    }
 
 	switch(priority)
 	{
@@ -859,9 +863,13 @@ void log_it_ex(LogContext *pContext, const int priority, const char *format, ...
 	va_start(ap, format); \
 	len = vsnprintf(text, sizeof(text), format, ap);  \
 	va_end(ap); \
+    if (len > sizeof(text)) \
+    { \
+        len = sizeof(text); \
+    } \
 	} \
 \
-	log_it_ex2(pContext, caption, text, len, bNeedSync, true); \
+	log_it_ex2(pContext, caption, text, len, bNeedSync, true);
 
 
 void logEmergEx(LogContext *pContext, const char *format, ...)
@@ -914,7 +922,10 @@ void logAccess(LogContext *pContext, struct timeval *tvStart, \
 	va_start(ap, format);
 	len = vsnprintf(text, sizeof(text), format, ap);
 	va_end(ap);
-
+    if (len > sizeof(text))
+    {
+        len = sizeof(text);
+    }
 	doLogEx(pContext, tvStart, NULL, text, len, false, true);
 }