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Avoid leakage of zero-length arrays in partition_bounds_copy().

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If ndatums is zero, the code would allocate zero-length boundKinds
and boundDatums chunks, which would have nothing pointing to them,
leading to Valgrind complaints.  Rearrange the code to avoid the
useless pallocs, and also to not bother computing byval/typlen when
they aren't used.

I'm unsure why I didn't see this in my Valgrind testing back in May.
This code hasn't changed since then, but maybe we added a regression
test that reaches this edge case.  Or possibly I just failed to
notice the reports, which do say "0 bytes lost".

Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/285483.1746756246@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2025-08-02 21:26:21 -04:00
parent b102c8c473
commit 4fbfdde58e
1 changed files with 30 additions and 29 deletions
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59
src/backend/partitioning/partbounds.c
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@ -1007,9 +1007,6 @@ partition_bounds_copy(PartitionBoundInfo src,
int ndatums;
int nindexes;
int partnatts;
bool hash_part;
int natts;
Datum *boundDatums;
dest = (PartitionBoundInfo) palloc(sizeof(PartitionBoundInfoData));
@ -1023,7 +1020,7 @@ partition_bounds_copy(PartitionBoundInfo src,
dest->datums = (Datum **) palloc(sizeof(Datum *) * ndatums);
if (src->kind != NULL)
if (src->kind != NULL && ndatums > 0)
{
PartitionRangeDatumKind *boundKinds;
@ -1058,36 +1055,40 @@ partition_bounds_copy(PartitionBoundInfo src,
* For hash partitioning, datums array will have two elements - modulus
* and remainder.
*/
hash_part = (key->strategy == PARTITION_STRATEGY_HASH);
natts = hash_part ? 2 : partnatts;
boundDatums = palloc(ndatums * natts * sizeof(Datum));
for (i = 0; i < ndatums; i++)
if (ndatums > 0)
{
int j;
bool hash_part = (key->strategy == PARTITION_STRATEGY_HASH);
int natts = hash_part ? 2 : partnatts;
Datum *boundDatums = palloc(ndatums * natts * sizeof(Datum));
dest->datums[i] = &boundDatums[i * natts];
for (j = 0; j < natts; j++)
for (i = 0; i < ndatums; i++)
{
bool byval;
int typlen;
int j;
if (hash_part)
{
typlen = sizeof(int32); /* Always int4 */
byval = true; /* int4 is pass-by-value */
}
else
{
byval = key->parttypbyval[j];
typlen = key->parttyplen[j];
}
dest->datums[i] = &boundDatums[i * natts];
if (dest->kind == NULL ||
dest->kind[i][j] == PARTITION_RANGE_DATUM_VALUE)
dest->datums[i][j] = datumCopy(src->datums[i][j],
byval, typlen);
for (j = 0; j < natts; j++)
{
if (dest->kind == NULL ||
dest->kind[i][j] == PARTITION_RANGE_DATUM_VALUE)
{
bool byval;
int typlen;
if (hash_part)
{
typlen = sizeof(int32); /* Always int4 */
byval = true; /* int4 is pass-by-value */
}
else
{
byval = key->parttypbyval[j];
typlen = key->parttyplen[j];
}
dest->datums[i][j] = datumCopy(src->datums[i][j],
byval, typlen);
}
}
}
}