From 15d6db4c64d641ec31f1dc2caa0fe1f0900b3887 Mon Sep 17 00:00:00 2001 From: Amit Kapila Date: Mon, 16 Dec 2019 15:23:46 +0530 Subject: [PATCH] Fix subscriber invalid memory access on DDL. This patch allows building the local relmap cache for a subscribed relation after processing pending invalidation messages and potential relcache updates. Without this, the attributes in the local cache don't tally with the updated relcache entry leading to invalid memory access. Reported-by Jehan-Guillaume de Rorthais Author: Jehan-Guillaume de Rorthais and Vignesh C Reviewed-by: Amit Kapila Backpatch-through: 10 Discussion: https://postgr.es/m/20191025175929.7e90dbf5@firost --- src/backend/replication/logical/relation.c | 40 +++++++++++++++++++----------- 1 file changed, 26 insertions(+), 14 deletions(-) diff --git a/src/backend/replication/logical/relation.c b/src/backend/replication/logical/relation.c index b386f84..ea47138 100644 --- a/src/backend/replication/logical/relation.c +++ b/src/backend/replication/logical/relation.c @@ -220,6 +220,8 @@ logicalrep_rel_open(LogicalRepRelId remoteid, LOCKMODE lockmode) { LogicalRepRelMapEntry *entry; bool found; + Oid relid = InvalidOid; + LogicalRepRelation *remoterel; if (LogicalRepRelMap == NULL) logicalrep_relmap_init(); @@ -232,20 +234,17 @@ logicalrep_rel_open(LogicalRepRelId remoteid, LOCKMODE lockmode) elog(ERROR, "no relation map entry for remote relation ID %u", remoteid); - /* Need to update the local cache? */ + remoterel = &entry->remoterel; + + /* + * When opening and locking a relation, pending invalidation messages are + * processed which can invalidate the relation. We need to update the + * local cache both when we are first time accessing the relation and when + * the relation is invalidated (aka entry->localreloid is set InvalidOid). + */ if (!OidIsValid(entry->localreloid)) { - Oid relid; - int i; - int found; - Bitmapset *idkey; - TupleDesc desc; - LogicalRepRelation *remoterel; - MemoryContext oldctx; - - remoterel = &entry->remoterel; - - /* Try to find and lock the relation by name. */ + /* Try to find and lock the relation by name */ relid = RangeVarGetRelid(makeRangeVar(remoterel->nspname, remoterel->relname, -1), lockmode, true); @@ -256,6 +255,21 @@ logicalrep_rel_open(LogicalRepRelId remoteid, LOCKMODE lockmode) remoterel->nspname, remoterel->relname))); entry->localrel = table_open(relid, NoLock); + } + else + { + relid = entry->localreloid; + entry->localrel = table_open(entry->localreloid, lockmode); + } + + if (!OidIsValid(entry->localreloid)) + { + int found; + Bitmapset *idkey; + TupleDesc desc; + MemoryContext oldctx; + int i; + /* Check for supported relkind. */ CheckSubscriptionRelkind(entry->localrel->rd_rel->relkind, remoterel->nspname, remoterel->relname); @@ -350,8 +364,6 @@ logicalrep_rel_open(LogicalRepRelId remoteid, LOCKMODE lockmode) entry->localreloid = relid; } - else - entry->localrel = table_open(entry->localreloid, lockmode); if (entry->state != SUBREL_STATE_READY) entry->state = GetSubscriptionRelState(MySubscription->oid, -- 1.8.3.1