[SERVER-70130] LockerImpl::endWriteUnitOfWork dereferences dangling reference Created: 30/Sep/22  Updated: 05/Dec/22  Resolved: 28/Oct/22

Status: Closed
Project: Core Server
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Bug Priority: Major - P3
Reporter: Jordi Serra Torrens Assignee: Backlog - Storage Execution Team
Resolution: Won't Fix Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Assigned Teams:
Storage Execution
Operating System: ALL
Participants:

 Description   

When 'unlockPending' reaches 1, this unlock call will free the slot, so then the next check on 'it->unlockPending > 0' will access a slot that's free to be reused.



 Comments   
Comment by Kaloian Manassiev [ 17/Oct/22 ]

It is not about that the iterator will be reused. It is more like that the slot to which this iterator points is technically "freed". This happens to work fine because we don't actually free the memory so the contents of that PODS are still valid, but it is just a bad programming practice.

More in this thread.

Comment by Matthew Saltz (Inactive) [ 04/Oct/22 ]

I think this might not actually be a bug, because LockerImpl use is single-threaded. So it's not possible for the iterator to actually be reused until endWriteUnitOfWork returns

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