commit e437a4fc345ca8e48f0cf77ebf450d32ec2a8aa1
Author: Zsolt Parragi <zsolt.parragi@percona.com>
Date:   Mon Mar 26 11:14:11 2018 +0200

    Fix bug 90238 / PS-3925 (Use strncmp instead of memcmp in log_in_use)
    
    (cherry picked from commit 2c950c3ca2bf890549825417c10dd3065b78befc)
    (cherry picked from commit 2fb17005e0d4b5d3c3c53d817e2be1c899a94e59)
    (cherry picked from commit 96f907bb235455521a11992675cdf12c9508d822)

diff --git a/sql/binlog.cc b/sql/binlog.cc
index ef99c2450f0..233e5a31664 100644
--- a/sql/binlog.cc
+++ b/sql/binlog.cc
@@ -2719,7 +2719,7 @@ class Log_in_use : public Do_THD_Impl {
     LOG_INFO *linfo;
     mysql_mutex_lock(&thd->LOCK_thd_data);
     if ((linfo = thd->current_linfo)) {
-      if (!memcmp(m_log_name, linfo->log_file_name, m_log_name_len)) {
+      if (!strncmp(m_log_name, linfo->log_file_name, m_log_name_len)) {
         LogErr(WARNING_LEVEL, ER_BINLOG_FILE_BEING_READ_NOT_PURGED, m_log_name,
                thd->thread_id());
         m_count++;