database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-09-02 04:21:28 +03:00
Code Activity

Fix possible crash during FATAL exit from reindexing.

Browse Source 
index.c supposed that it could just use a PG_TRY block to clean up the
state associated with an active REINDEX operation.  However, that code
doesn't run if we do a FATAL exit --- for example, due to a SIGTERM
shutdown signal --- while the REINDEX is happening.  And that state does
get consulted during catalog accesses, which makes it problematic if we
do any catalog accesses during shutdown --- for example, to clean up any
temp tables created in the session.

If this combination of circumstances occurred, we could find ourselves
trying to access already-freed memory.  In debug builds that'd fairly
reliably cause an assertion failure.  In production we might often
get away with it, but with some bad luck it could cause a core dump.

Another possible bad outcome is an erroneous conclusion that an
index-to-be-accessed is being reindexed; but it looks like that would
be unlikely to have any consequences worse than failing to drop temp
tables right away.  (They'd still get dropped by the next session that
uses that temp schema.)

To fix, get rid of the use of PG_TRY here, and instead hook into
the transaction abort mechanisms to clean up reindex state.

Per bug #16378 from Alexander Lakhin.  This has been wrong for a
very long time, so back-patch to all supported branches.

Discussion: https://postgr.es/m/16378-7a70ca41b3ec2009@postgresql.org
This commit is contained in:
Tom Lane
2020-04-21 15:58:42 -04:00
parent 90abbba074
commit 5a4efd100a
3 changed files with 108 additions and 99 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
src/include/catalog/index.h
View File

@@ -131,6 +131,8 @@ extern void validate_index(Oid heapId, Oid indexId, Snapshot snapshot);
extern void index_set_state_flags(Oid indexId, IndexStateFlagsAction action);
extern Oid IndexGetRelation(Oid indexId, bool missing_ok);
extern void reindex_index(Oid indexId, bool skip_constraint_checks,
char relpersistence, int options);
@@ -145,8 +147,8 @@ extern bool reindex_relation(Oid relid, int flags, int options);
extern bool ReindexIsProcessingHeap(Oid heapOid);
extern bool ReindexIsProcessingIndex(Oid indexOid);
extern Oid IndexGetRelation(Oid indexId, bool missing_ok);
extern void ResetReindexState(int nestLevel);
extern Size EstimateReindexStateSpace(void);
extern void SerializeReindexState(Size maxsize, char *start_address);
extern void RestoreReindexState(void *reindexstate);