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Avoid memcpy() with a NULL source pointer and count == 0 

When memcpy() is called on a pointer, the compiler is entitled to assume
that the pointer is not null, which can lead to optimizing nearby code
in potentially undesirable ways.  We still want such optimizations
(gcc's -fdelete-null-pointer-checks) in cases where they're valid.

Related: commit 13bba02271.

Backpatch to pg11, where this particular instance appeared.

Reported-by: Ranier Vilela <ranier.vf@gmail.com>
Reported-by: Zhihong Yu <zyu@yugabyte.com>
Discussion: https://postgr.es/m/CAEudQApUndmQkr5fLrCKXQ7+ib44i7S+Kk93pyVThS85PnG3bQ@mail.gmail.com
Discussion: https://postgr.es/m/CALNJ-vSdhwSM5f4tnNn1cdLHvXMVe_S+V3nR5GwNrmCPNB2VtQ@mail.gmail.com
This commit is contained in:
Alvaro Herrera 2020-12-01 11:46:56 -03:00
parent 415dc20096
commit 677f74e5bb
No known key found for this signature in database
GPG Key ID: 1C20ACB9D5C564AE
1 changed files with 4 additions and 2 deletions
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6
src/backend/commands/indexcmds.c
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@ -1163,15 +1163,17 @@ DefineIndex(Oid relationId,
if (partitioned) if (partitioned)
{ {
PartitionDesc partdesc;
/* /*
* Unless caller specified to skip this step (via ONLY), process each * Unless caller specified to skip this step (via ONLY), process each
* partition to make sure they all contain a corresponding index. * partition to make sure they all contain a corresponding index.
* *
* If we're called internally (no stmt->relation), recurse always. * If we're called internally (no stmt->relation), recurse always.
*/ */
if (!stmt->relation || stmt->relation->inh) partdesc = RelationGetPartitionDesc(rel);
if ((!stmt->relation || stmt->relation->inh) && partdesc->nparts > 0)
{ {
PartitionDesc partdesc = RelationGetPartitionDesc(rel);
int nparts = partdesc->nparts; int nparts = partdesc->nparts;
Oid *part_oids = palloc(sizeof(Oid) * nparts); Oid *part_oids = palloc(sizeof(Oid) * nparts);
bool invalidate_parent = false; bool invalidate_parent = false;