mirror of
https://github.com/postgres/postgres.git
synced 2025-12-19 17:02:53 +03:00
ef5f559b95
In commit b61aa76e4 I added an assumption in jsonb_object_agg_finalfn
that it'd be okay to apply uniqueifyJsonbObject repeatedly to a
JsonbValue. I should have studied that code more closely first,
because in skip_nulls mode it removed leading nulls by changing the
"pairs" array start pointer. This broke the data structure's
invariants in two ways: pairs no longer references a repalloc-able
chunk, and the distance from pairs to the end of its array is less
than parseState->size. So any subsequent addition of more pairs is
at high risk of clobbering memory and/or causing repalloc to crash.
Unfortunately, adding more pairs is exactly what will happen when the
aggregate is being used as a window function.
Fix by rewriting uniqueifyJsonbObject to not do that. The prior
coding had little to recommend it anyway.
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/ec5e96fb-ee49-4e5f-8a09-3f72b4780538@gmail.com