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.

diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index 0bba9a7dbdaef765292fc528062315017586b859..934dba88c668d07ea556972809de9bd05b927c78 100644 (file)
--- 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 6df62a7dccb77ccd31facd7d886fef8282079b2a..f03cd9b07b3883849dd50ececb2c35bf549d11c5 100644 (file)
--- 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;