Incremental selection may not work properly for LCS and ICS due to an
use-after-free bug in partitioned set which came into existence after
compound set was introduced.
The use-after-free happens because partitioned set wasn't taking into
account that the next position can become the current position in the
next iteration, which will be used by all selectors managed by
compound set. So if next position is freed, when it were being used
as current position, subsequent selectors would find the current
position freed, making them produce incorrect results.
Fix this by moving ownership of next pos from incremental_selector_impl
to incremental_selector, which makes it more robust as the latter knows
better when the selection is done with the next pos. incremental_selector
will still return ring_position_view to avoid copies.
Fixes#8802.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Message-Id: <20210611130957.156712-1-raphaelsc@scylladb.com>
846f0bd16e