Fix race in ReplicationSlotRelease() for ephemeral slots When releasing an ephemeral replication slot, ReplicationSlotRelease() drops the slot via ReplicationSlotDropAcquired().
However, after dropping the slot, ReplicationSlotRelease() continued to use its local "slot" pointer, which still referenced the dropped slot's former shared-memory entry. It could then update fields such as effective_xmin in that entry. Once an ephemeral slot has been dropped (via ReplicationSlotDropAcquired()), its slot array entry can be reused immediately by another backend creating a new slot. As a result, those updates could corrupt the state of an unrelated replication slot. Fix by skipping those shared-memory updates for phemeral slots and performing them only for non-ephemeral slots, whose shared-memory entries remain valid after release. Backpatch to all supported versions. Author: Zhijie Hou <[email protected]> Reviewed-by: Masao Fujii <[email protected]> Reviewed-by: Srinath Reddy Sadipiralla <[email protected]> Reviewed-by: Xuneng Zhou <[email protected]> Discussion: https://postgr.es/m/ty4pr01mb177184ff9ee916f577e1f554194...@ty4pr01mb17718.jpnprd01.prod.outlook.com Backpatch-through: 14 Branch ------ REL_18_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/f833c92077a1ba7fd8bb5d51dc466409e2fd33b0 Modified Files -------------- src/backend/replication/slot.c | 68 ++++++++++++++++++++++-------------------- 1 file changed, 35 insertions(+), 33 deletions(-)
