mirror of https://github.com/postgres/postgres
Fix null-pointer crash in postgres_fdw's conversion_error_callback.
Commit c7b7311f6 adjusted conversion_error_callback to always use
information from the query's rangetable, to avoid doing catalog lookups
in an already-failed transaction. However, as a result of the utterly
inadequate documentation for make_tuple_from_result_row, I failed to
realize that fsstate could be NULL in some contexts. That led to a
crash if we got a conversion error in such a context. Fix by falling
back to the previous coding when fsstate is NULL. Improve the
commentary, too.
Per report from Andrey Borodin. Back-patch to 9.6, like the previous
patch.
Discussion: https://postgr.es/m/08916396-55E4-4D68-AB3A-BD6066F9E5C0@yandex-team.ru
This commit is contained in:
Tom Lane
parent
db692b0c84
commit
3071bbfe44
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@ -4200,6 +4200,9 @@ CONTEXT: whole-row reference to foreign table "ftx"
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SELECT sum(c2), array_agg(c8) FROM ft1 GROUP BY c8; -- ERROR
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ERROR: invalid input syntax for type integer: "foo"
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CONTEXT: processing expression at position 2 in select list
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ANALYZE ft1; -- ERROR
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ERROR: invalid input syntax for type integer: "foo"
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CONTEXT: column "c8" of foreign table "ft1"
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ALTER FOREIGN TABLE ft1 ALTER COLUMN c8 TYPE user_enum;
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-- ===================================================================
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-- subtransaction
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@ -303,7 +303,8 @@ typedef struct
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typedef struct ConversionLocation
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{
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AttrNumber cur_attno; /* attribute number being processed, or 0 */
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ForeignScanState *fsstate; /* plan node being processed */
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Relation rel; /* foreign table being processed, or NULL */
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ForeignScanState *fsstate; /* plan node being processed, or NULL */
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} ConversionLocation;
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/* Callback argument for ec_member_matches_foreign */
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@ -7113,7 +7114,12 @@ complete_pending_request(AsyncRequest *areq)
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* rel is the local representation of the foreign table, attinmeta is
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* conversion data for the rel's tupdesc, and retrieved_attrs is an
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* integer list of the table column numbers present in the PGresult.
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* fsstate is the ForeignScan plan node's execution state.
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* temp_context is a working context that can be reset after each tuple.
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*
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* Note: either rel or fsstate, but not both, can be NULL. rel is NULL
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* if we're processing a remote join, while fsstate is NULL in a non-query
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* context such as ANALYZE, or if we're processing a non-scan query node.
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*/
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static HeapTuple
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make_tuple_from_result_row(PGresult *res,
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@ -7144,6 +7150,10 @@ make_tuple_from_result_row(PGresult *res,
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*/
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oldcontext = MemoryContextSwitchTo(temp_context);
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/*
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* Get the tuple descriptor for the row. Use the rel's tupdesc if rel is
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* provided, otherwise look to the scan node's ScanTupleSlot.
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*/
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if (rel)
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tupdesc = RelationGetDescr(rel);
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else
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@ -7161,6 +7171,7 @@ make_tuple_from_result_row(PGresult *res,
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* Set up and install callback to report where conversion error occurs.
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*/
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errpos.cur_attno = 0;
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errpos.rel = rel;
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errpos.fsstate = fsstate;
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errcallback.callback = conversion_error_callback;
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errcallback.arg = (void *) &errpos;
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@ -7265,60 +7276,87 @@ make_tuple_from_result_row(PGresult *res,
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*
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* Note that this function mustn't do any catalog lookups, since we are in
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* an already-failed transaction. Fortunately, we can get the needed info
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* from the query's rangetable instead.
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* from the relation or the query's rangetable instead.
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*/
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static void
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conversion_error_callback(void *arg)
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{
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ConversionLocation *errpos = (ConversionLocation *) arg;
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Relation rel = errpos->rel;
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ForeignScanState *fsstate = errpos->fsstate;
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ForeignScan *fsplan = castNode(ForeignScan, fsstate->ss.ps.plan);
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int varno = 0;
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AttrNumber colno = 0;
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const char *attname = NULL;
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const char *relname = NULL;
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bool is_wholerow = false;
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if (fsplan->scan.scanrelid > 0)
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/*
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* If we're in a scan node, always use aliases from the rangetable, for
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* consistency between the simple-relation and remote-join cases. Look at
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* the relation's tupdesc only if we're not in a scan node.
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*/
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if (fsstate)
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{
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/* error occurred in a scan against a foreign table */
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varno = fsplan->scan.scanrelid;
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colno = errpos->cur_attno;
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}
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else
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{
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/* error occurred in a scan against a foreign join */
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TargetEntry *tle;
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/* ForeignScan case */
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ForeignScan *fsplan = castNode(ForeignScan, fsstate->ss.ps.plan);
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int varno = 0;
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AttrNumber colno = 0;
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tle = list_nth_node(TargetEntry, fsplan->fdw_scan_tlist,
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errpos->cur_attno - 1);
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/*
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* Target list can have Vars and expressions. For Vars, we can get
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* some information, however for expressions we can't. Thus for
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* expressions, just show generic context message.
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*/
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if (IsA(tle->expr, Var))
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if (fsplan->scan.scanrelid > 0)
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{
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Var *var = (Var *) tle->expr;
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/* error occurred in a scan against a foreign table */
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varno = fsplan->scan.scanrelid;
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colno = errpos->cur_attno;
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}
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else
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{
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/* error occurred in a scan against a foreign join */
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TargetEntry *tle;
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varno = var->varno;
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colno = var->varattno;
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tle = list_nth_node(TargetEntry, fsplan->fdw_scan_tlist,
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errpos->cur_attno - 1);
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/*
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* Target list can have Vars and expressions. For Vars, we can
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* get some information, however for expressions we can't. Thus
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* for expressions, just show generic context message.
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*/
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if (IsA(tle->expr, Var))
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{
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Var *var = (Var *) tle->expr;
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varno = var->varno;
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colno = var->varattno;
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}
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}
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if (varno > 0)
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{
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EState *estate = fsstate->ss.ps.state;
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RangeTblEntry *rte = exec_rt_fetch(varno, estate);
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relname = rte->eref->aliasname;
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if (colno == 0)
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is_wholerow = true;
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else if (colno > 0 && colno <= list_length(rte->eref->colnames))
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attname = strVal(list_nth(rte->eref->colnames, colno - 1));
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else if (colno == SelfItemPointerAttributeNumber)
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attname = "ctid";
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}
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}
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if (varno > 0)
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else if (rel)
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{
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EState *estate = fsstate->ss.ps.state;
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RangeTblEntry *rte = exec_rt_fetch(varno, estate);
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/* Non-ForeignScan case (we should always have a rel here) */
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TupleDesc tupdesc = RelationGetDescr(rel);
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relname = rte->eref->aliasname;
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relname = RelationGetRelationName(rel);
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if (errpos->cur_attno > 0 && errpos->cur_attno <= tupdesc->natts)
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{
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Form_pg_attribute attr = TupleDescAttr(tupdesc,
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errpos->cur_attno - 1);
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if (colno == 0)
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is_wholerow = true;
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else if (colno > 0 && colno <= list_length(rte->eref->colnames))
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attname = strVal(list_nth(rte->eref->colnames, colno - 1));
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else if (colno == SelfItemPointerAttributeNumber)
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attname = NameStr(attr->attname);
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}
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else if (errpos->cur_attno == SelfItemPointerAttributeNumber)
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attname = "ctid";
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}
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@ -1164,6 +1164,7 @@ SELECT ftx.x1, ft2.c2, ftx.x8 FROM ft1 ftx(x1,x2,x3,x4,x5,x6,x7,x8), ft2
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SELECT ftx.x1, ft2.c2, ftx FROM ft1 ftx(x1,x2,x3,x4,x5,x6,x7,x8), ft2
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WHERE ftx.x1 = ft2.c1 AND ftx.x1 = 1; -- ERROR
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SELECT sum(c2), array_agg(c8) FROM ft1 GROUP BY c8; -- ERROR
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ANALYZE ft1; -- ERROR
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ALTER FOREIGN TABLE ft1 ALTER COLUMN c8 TYPE user_enum;
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-- ===================================================================
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