[IMPALA-11365] Dereferencing null pointer in TopNNode

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Impala 4.2.0, Impala 4.1.1
• Epic Color: ghx-label-3
• Assignee: Daniel Becker
• Reporter: Daniel Becker
• Created: 16/Jun/22 14:51
• Updated: 23/Aug/22 05:48
• Resolved: 22/Jun/22 09:23

Description

In the constructor of TopNNode, if pnode.partition_comparator_config_ is NULL, we initialise partition_cmp_ with a NULL pointer. However, when initialising partition_heaps_, we dereference partition_cmp_ because ComparatorWrapper expects a reference.

This has so far not lead to a crash because in this case the comparator of partition_heaps_ is not used, but assigning a NULL pointer to a reference is undefined behaviour.