[ZOOKEEPER-888] c-client / zkpython: Double free corruption on node watcher

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 3.3.1
• Fix Version/s: 3.3.2, 3.3.3, 3.4.0
• Component/s: c client, contrib-bindings
• Hadoop Flags: Reviewed
• Assignee: Lukas
• Reporter: Lukas
• Created: 06/Oct/10 13:26
• Updated: 23/Nov/11 19:22
• Resolved: 19/Oct/10 19:02

Description

the c-client / zkpython wrapper invokes already freed watcher callback

steps to reproduce:
0. start a zookeper server on your machine
1. run the attached python script
2. suspend the zookeeper server process (e.g. using `pkill -STOP -f org.apache.zookeeper.server.quorum.QuorumPeerMain` )
3. wait until the connection and the node observer fired with a session event
4. resume the zookeeper server process (e.g. using `pkill -CONT -f org.apache.zookeeper.server.quorum.QuorumPeerMain` )

-> the client tries to dispatch the node observer function again, but it was already freed -> double free corruption

Issue Links

• duplicates: ZOOKEEPER-740 zkpython leading to segfault on zookeeper
• is duplicated by: ZOOKEEPER-890 C client invokes watcher callbacks multiple times