[LOG4J2-3471] log4j-1.2-api 2.17.2 throws NullPointerException while removing appender with name as null

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.17.2
• Fix Version/s: 2.18.0
• Assignee: Gary D. Gregory
• Reporter: Rajesh
• Created: 07/Apr/22 15:57
• Updated: 02/May/22 21:12
• Resolved: 07/Apr/22 20:50

Description

The log4j 1.2 bridge for 2.17.2 throws null pointer exception while removing Null appender

viz. org.apache.log4j.varia.NullAppender 

The class AppenderAttachableImpl adds the null appender to the concurrenthashmap as "null" and on removal there is no check for null and removes the nullappender with name null hence the NullPointerexception.

Caused by: java.lang.NullPointerException
at java.util.concurrent.ConcurrentHashMap.remove(Unknown Source)
at org.apache.log4j.helpers.AppenderAttachableImpl.removeAppender(AppenderAttachableImpl.java:93)
at org.apache.log4j.Category.removeAppender(Category.java:618)