From acefa2cca6a2c2b9c0fd9f25d0c003595bed689e Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Mon, 8 Jun 2020 13:57:24 +1200 Subject: [PATCH] Fix locking bugs that could corrupt pg_control. The redo routines for XLOG_CHECKPOINT_{ONLINE,SHUTDOWN} must acquire ControlFileLock before modifying ControlFile->checkPointCopy, or the checkpointer could write out a control file with a bad checksum. Likewise, XLogReportParameters() must acquire ControlFileLock before modifying ControlFile and calling UpdateControlFile(). Back-patch to all supported releases. Author: Nathan Bossart Author: Fujii Masao Reviewed-by: Fujii Masao Reviewed-by: Michael Paquier Reviewed-by: Thomas Munro Discussion: https://postgr.es/m/70BF24D6-DC51-443F-B55A-95735803842A%40amazon.com --- src/backend/access/transam/xlog.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index ca09d81b08..55cac186dc 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -9743,6 +9743,8 @@ XLogReportParameters(void) XLogFlush(recptr); } + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); + ControlFile->MaxConnections = MaxConnections; ControlFile->max_worker_processes = max_worker_processes; ControlFile->max_wal_senders = max_wal_senders; @@ -9752,6 +9754,8 @@ XLogReportParameters(void) ControlFile->wal_log_hints = wal_log_hints; ControlFile->track_commit_timestamp = track_commit_timestamp; UpdateControlFile(); + + LWLockRelease(ControlFileLock); } } @@ -9976,7 +9980,9 @@ xlog_redo(XLogReaderState *record) } /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); ControlFile->checkPointCopy.nextFullXid = checkPoint.nextFullXid; + LWLockRelease(ControlFileLock); /* Update shared-memory copy of checkpoint XID/epoch */ SpinLockAcquire(&XLogCtl->info_lck); @@ -10033,7 +10039,9 @@ xlog_redo(XLogReaderState *record) SetTransactionIdLimit(checkPoint.oldestXid, checkPoint.oldestXidDB); /* ControlFile->checkPointCopy always tracks the latest ckpt XID */ + LWLockAcquire(ControlFileLock, LW_EXCLUSIVE); ControlFile->checkPointCopy.nextFullXid = checkPoint.nextFullXid; + LWLockRelease(ControlFileLock); /* Update shared-memory copy of checkpoint XID/epoch */ SpinLockAcquire(&XLogCtl->info_lck);