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Commit012b80a

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Fix exception safety bug in typcache.c.
If an out-of-memory error was thrown at an unfortunate time,ensure_record_cache_typmod_slot_exists() could leak memory and leavebehind a global state that produced an infinite loop on the next call.Fix by merging RecordCacheArray and RecordIdentifierArray into a singlearray. With only one allocation or re-allocation, there is nointermediate state.Back-patch to all supported releases.Reported-by: "James Pang (chaolpan)" <chaolpan@cisco.com>Reviewed-by: Michael Paquier <michael@paquier.xyz>Discussion:https://postgr.es/m/PH0PR11MB519113E738814BDDA702EDADD6EFA%40PH0PR11MB5191.namprd11.prod.outlook.com
1 parent7e57208 commit012b80a

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2 files changed

+27
-26
lines changed

2 files changed

+27
-26
lines changed

‎src/backend/utils/cache/typcache.c‎

Lines changed: 26 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -263,10 +263,15 @@ static const dshash_parameters srtr_typmod_table_params = {
263263
/* hashtable for recognizing registered record types */
264264
staticHTAB*RecordCacheHash=NULL;
265265

266-
/* arrays of info about registered record types, indexed by assigned typmod */
267-
staticTupleDesc*RecordCacheArray=NULL;
268-
staticuint64*RecordIdentifierArray=NULL;
269-
staticint32RecordCacheArrayLen=0;/* allocated length of above arrays */
266+
typedefstructRecordCacheArrayEntry
267+
{
268+
uint64id;
269+
TupleDesctupdesc;
270+
}RecordCacheArrayEntry;
271+
272+
/* array of info about registered record types, indexed by assigned typmod */
273+
staticRecordCacheArrayEntry*RecordCacheArray=NULL;
274+
staticint32RecordCacheArrayLen=0;/* allocated length of above array */
270275
staticint32NextRecordTypmod=0;/* number of entries used */
271276

272277
/*
@@ -1525,10 +1530,8 @@ ensure_record_cache_typmod_slot_exists(int32 typmod)
15251530
{
15261531
if (RecordCacheArray==NULL)
15271532
{
1528-
RecordCacheArray= (TupleDesc*)
1529-
MemoryContextAllocZero(CacheMemoryContext,64*sizeof(TupleDesc));
1530-
RecordIdentifierArray= (uint64*)
1531-
MemoryContextAllocZero(CacheMemoryContext,64*sizeof(uint64));
1533+
RecordCacheArray= (RecordCacheArrayEntry*)
1534+
MemoryContextAllocZero(CacheMemoryContext,64*sizeof(RecordCacheArrayEntry));
15321535
RecordCacheArrayLen=64;
15331536
}
15341537

@@ -1539,14 +1542,11 @@ ensure_record_cache_typmod_slot_exists(int32 typmod)
15391542
while (typmod >=newlen)
15401543
newlen *=2;
15411544

1542-
RecordCacheArray= (TupleDesc*)repalloc(RecordCacheArray,
1543-
newlen*sizeof(TupleDesc));
1545+
RecordCacheArray= (RecordCacheArrayEntry*)
1546+
repalloc(RecordCacheArray,
1547+
newlen*sizeof(RecordCacheArrayEntry));
15441548
memset(RecordCacheArray+RecordCacheArrayLen,0,
1545-
(newlen-RecordCacheArrayLen)*sizeof(TupleDesc));
1546-
RecordIdentifierArray= (uint64*)repalloc(RecordIdentifierArray,
1547-
newlen*sizeof(uint64));
1548-
memset(RecordIdentifierArray+RecordCacheArrayLen,0,
1549-
(newlen-RecordCacheArrayLen)*sizeof(uint64));
1549+
(newlen-RecordCacheArrayLen)*sizeof(RecordCacheArrayEntry));
15501550
RecordCacheArrayLen=newlen;
15511551
}
15521552
}
@@ -1584,8 +1584,8 @@ lookup_rowtype_tupdesc_internal(Oid type_id, int32 typmod, bool noError)
15841584
{
15851585
/* It is already in our local cache? */
15861586
if (typmod<RecordCacheArrayLen&&
1587-
RecordCacheArray[typmod]!=NULL)
1588-
returnRecordCacheArray[typmod];
1587+
RecordCacheArray[typmod].tupdesc!=NULL)
1588+
returnRecordCacheArray[typmod].tupdesc;
15891589

15901590
/* Are we attached to a shared record typmod registry? */
15911591
if (CurrentSession->shared_typmod_registry!=NULL)
@@ -1611,19 +1611,19 @@ lookup_rowtype_tupdesc_internal(Oid type_id, int32 typmod, bool noError)
16111611
* Our local array can now point directly to the TupleDesc
16121612
* in shared memory, which is non-reference-counted.
16131613
*/
1614-
RecordCacheArray[typmod]=tupdesc;
1614+
RecordCacheArray[typmod].tupdesc=tupdesc;
16151615
Assert(tupdesc->tdrefcount==-1);
16161616

16171617
/*
16181618
* We don't share tupdesc identifiers across processes, so
16191619
* assign one locally.
16201620
*/
1621-
RecordIdentifierArray[typmod]=++tupledesc_id_counter;
1621+
RecordCacheArray[typmod].id=++tupledesc_id_counter;
16221622

16231623
dshash_release_lock(CurrentSession->shared_typmod_table,
16241624
entry);
16251625

1626-
returnRecordCacheArray[typmod];
1626+
returnRecordCacheArray[typmod].tupdesc;
16271627
}
16281628
}
16291629
}
@@ -1834,10 +1834,10 @@ assign_record_type_typmod(TupleDesc tupDesc)
18341834
ensure_record_cache_typmod_slot_exists(entDesc->tdtypmod);
18351835
}
18361836

1837-
RecordCacheArray[entDesc->tdtypmod]=entDesc;
1837+
RecordCacheArray[entDesc->tdtypmod].tupdesc=entDesc;
18381838

18391839
/* Assign a unique tupdesc identifier, too. */
1840-
RecordIdentifierArray[entDesc->tdtypmod]=++tupledesc_id_counter;
1840+
RecordCacheArray[entDesc->tdtypmod].id=++tupledesc_id_counter;
18411841

18421842
/* Fully initialized; create the hash table entry */
18431843
recentry= (RecordCacheEntry*)hash_search(RecordCacheHash,
@@ -1886,10 +1886,10 @@ assign_record_type_identifier(Oid type_id, int32 typmod)
18861886
* It's a transient record type, so look in our record-type table.
18871887
*/
18881888
if (typmod >=0&&typmod<RecordCacheArrayLen&&
1889-
RecordCacheArray[typmod]!=NULL)
1889+
RecordCacheArray[typmod].tupdesc!=NULL)
18901890
{
1891-
Assert(RecordIdentifierArray[typmod]!=0);
1892-
returnRecordIdentifierArray[typmod];
1891+
Assert(RecordCacheArray[typmod].id!=0);
1892+
returnRecordCacheArray[typmod].id;
18931893
}
18941894

18951895
/* For anonymous or unrecognized record type, generate a new ID */
@@ -1969,7 +1969,7 @@ SharedRecordTypmodRegistryInit(SharedRecordTypmodRegistry *registry,
19691969
TupleDesctupdesc;
19701970
boolfound;
19711971

1972-
tupdesc=RecordCacheArray[typmod];
1972+
tupdesc=RecordCacheArray[typmod].tupdesc;
19731973
if (tupdesc==NULL)
19741974
continue;
19751975

‎src/tools/pgindent/typedefs.list‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1965,6 +1965,7 @@ ReadExtraTocPtrType
19651965
ReadFunc
19661966
ReassignOwnedStmt
19671967
RecheckForeignScan_function
1968+
RecordCacheArrayEntry
19681969
RecordCacheEntry
19691970
RecordCompareData
19701971
RecordIOData

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