types: fix potential use after free on adding keys during iteration#239
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When keys are added to the object currently being iterated by a for loop, the insert operation might cause a hashtable resize with a subsequent memory reallocation and a different table base pointer, clobbering the entry pointers held by iterators pointing to the containing object of the resized table. In order to address this issue while keeping the iteration overhead low, extend the object key insert logic to check whether the insertion will trigger a reallocation and backup and restore the iterator pointers when needed. This slightly increases the size of the iterator states but the overhead for this should be neglectible as there'll only be a low amount of concurrently active iterations at any time. Fixes: #230 Signed-off-by: Jo-Philipp Wich <jo@mein.io>
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When keys are added to the object currently being iterated by a for loop, the insert operation might cause a hashtable resize with a subsequent memory reallocation and a different table base pointer, clobbering the entry pointers held by iterators pointing to the containing object of the resized table.
In order to address this issue while keeping the iteration overhead low, extend the object key insert logic to check whether the insertion will trigger a reallocation and backup and restore the iterator pointers when needed.
This slightly increases the size of the iterator states but the overhead for this should be neglectible as there'll only be a low amount of concurrently active iterations at any time.
Fixes: #230