From 06bd458cb812623c3f1fdd55216c4c08b06a8447 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 6 May 2016 14:23:47 -0400
Subject: [PATCH] Use mul_size when multiplying by the number of parallel
workers.
That way, if the result overflows size_t, you'll get an error instead
of undefined behavior, which seems like a plus. This also has the
effect of casting the number of workers from int to Size, which is
better because it's harder to overflow int than size_t.
Dilip Kumar reported this issue and provided a patch upon which this
patch is based, but his version did use mul_size.
---
src/backend/access/transam/parallel.c | 6 ++++--
src/backend/executor/execParallel.c | 18 +++++++++++-------
2 files changed, 15 insertions(+), 9 deletions(-)
diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index 0bba9a7dbda..934dba88c66 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -241,7 +241,8 @@ InitializeParallelDSM(ParallelContext *pcxt)
PARALLEL_ERROR_QUEUE_SIZE,
"parallel error queue size not buffer-aligned");
shm_toc_estimate_chunk(&pcxt->estimator,
- PARALLEL_ERROR_QUEUE_SIZE * pcxt->nworkers);
+ mul_size(PARALLEL_ERROR_QUEUE_SIZE,
+ pcxt->nworkers));
shm_toc_estimate_keys(&pcxt->estimator, 1);
/* Estimate how much we'll need for extension entrypoint info. */
@@ -347,7 +348,8 @@ InitializeParallelDSM(ParallelContext *pcxt)
*/
error_queue_space =
shm_toc_allocate(pcxt->toc,
- PARALLEL_ERROR_QUEUE_SIZE * pcxt->nworkers);
+ mul_size(PARALLEL_ERROR_QUEUE_SIZE,
+ pcxt->nworkers));
for (i = 0; i < pcxt->nworkers; ++i)
{
char *start;
diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index 6df62a7dccb..f03cd9b07b3 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -287,7 +287,8 @@ ExecParallelSetupTupleQueues(ParallelContext *pcxt, bool reinitialize)
if (!reinitialize)
tqueuespace =
shm_toc_allocate(pcxt->toc,
- PARALLEL_TUPLE_QUEUE_SIZE * pcxt->nworkers);
+ mul_size(PARALLEL_TUPLE_QUEUE_SIZE,
+ pcxt->nworkers));
else
tqueuespace = shm_toc_lookup(pcxt->toc, PARALLEL_KEY_TUPLE_QUEUE);
@@ -296,7 +297,8 @@ ExecParallelSetupTupleQueues(ParallelContext *pcxt, bool reinitialize)
{
shm_mq *mq;
- mq = shm_mq_create(tqueuespace + i * PARALLEL_TUPLE_QUEUE_SIZE,
+ mq = shm_mq_create(tqueuespace +
+ ((Size) i) * PARALLEL_TUPLE_QUEUE_SIZE,
(Size) PARALLEL_TUPLE_QUEUE_SIZE);
shm_mq_set_receiver(mq, MyProc);
@@ -380,12 +382,12 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers)
* looking at pgBufferUsage, so do it unconditionally.
*/
shm_toc_estimate_chunk(&pcxt->estimator,
- sizeof(BufferUsage) * pcxt->nworkers);
+ mul_size(sizeof(BufferUsage), pcxt->nworkers));
shm_toc_estimate_keys(&pcxt->estimator, 1);
/* Estimate space for tuple queues. */
shm_toc_estimate_chunk(&pcxt->estimator,
- PARALLEL_TUPLE_QUEUE_SIZE * pcxt->nworkers);
+ mul_size(PARALLEL_TUPLE_QUEUE_SIZE, pcxt->nworkers));
shm_toc_estimate_keys(&pcxt->estimator, 1);
/*
@@ -404,7 +406,9 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers)
sizeof(int) * e.nnodes;
instrumentation_len = MAXALIGN(instrumentation_len);
instrument_offset = instrumentation_len;
- instrumentation_len += sizeof(Instrumentation) * e.nnodes * nworkers;
+ instrumentation_len +=
+ mul_size(sizeof(Instrumentation),
+ mul_size(e.nnodes, nworkers));
shm_toc_estimate_chunk(&pcxt->estimator, instrumentation_len);
shm_toc_estimate_keys(&pcxt->estimator, 1);
}
@@ -432,7 +436,7 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers)
/* Allocate space for each worker's BufferUsage; no need to initialize. */
bufusage_space = shm_toc_allocate(pcxt->toc,
- sizeof(BufferUsage) * pcxt->nworkers);
+ mul_size(sizeof(BufferUsage), pcxt->nworkers));
shm_toc_insert(pcxt->toc, PARALLEL_KEY_BUFFER_USAGE, bufusage_space);
pei->buffer_usage = bufusage_space;
@@ -511,7 +515,7 @@ ExecParallelRetrieveInstrumentation(PlanState *planstate,
InstrAggNode(planstate->instrument, &instrument[n]);
/* Also store the per-worker detail. */
- ibytes = instrumentation->num_workers * sizeof(Instrumentation);
+ ibytes = mul_size(instrumentation->num_workers, sizeof(Instrumentation));
planstate->worker_instrument =
palloc(ibytes + offsetof(WorkerInstrumentation, instrument));
planstate->worker_instrument->num_workers = instrumentation->num_workers;
--
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