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Commit46af71f

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Fix incorrect logic in plpgsql for cleanup after evaluation of non-simple
expressions. We need to deal with this when handling subscripts in an arrayassignment, and also when catching an exception. In an Assert-enabled buildthese omissions led to Assert failures, but I think in a normal build theonly consequence would be short-term memory leakage; which may explain whythis wasn't reported from the field long ago.Back-patch to all supported versions. 7.4 doesn't have exceptions, butotherwise these bugs go all the way back.Heikki Linnakangas and Tom Lane
1 parent4773198 commit46af71f

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3 files changed

+123
-3
lines changed

3 files changed

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‎src/pl/plpgsql/src/pl_exec.c‎

Lines changed: 40 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.262 2010/08/0902:25:05 tgl Exp $
11+
* $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.263 2010/08/0918:50:10 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -1099,6 +1099,9 @@ exec_stmt_block(PLpgSQL_execstate *estate, PLpgSQL_stmt_block *block)
10991099
*/
11001100
SPI_restore_connection();
11011101

1102+
/* Must clean up the econtext too */
1103+
exec_eval_cleanup(estate);
1104+
11021105
/* Look for a matching exception handler */
11031106
foreach(e,block->exceptions->exc_list)
11041107
{
@@ -2701,6 +2704,9 @@ plpgsql_estate_setup(PLpgSQL_execstate *estate,
27012704
*
27022705
* NB: the result of the evaluation is no longer valid after this is done,
27032706
* unless it is a pass-by-value datatype.
2707+
*
2708+
* NB: if you change this code, see also the hacks in exec_assign_value's
2709+
* PLPGSQL_DTYPE_ARRAYELEM case.
27042710
* ----------
27052711
*/
27062712
staticvoid
@@ -3464,6 +3470,10 @@ exec_assign_expr(PLpgSQL_execstate *estate, PLpgSQL_datum *target,
34643470

34653471
/* ----------
34663472
* exec_assign_valuePut a value into a target field
3473+
*
3474+
* Note: in some code paths, this may leak memory in the eval_econtext;
3475+
* we assume that will be cleaned up later by exec_eval_cleanup. We cannot
3476+
* call exec_eval_cleanup here for fear of destroying the input Datum value.
34673477
* ----------
34683478
*/
34693479
staticvoid
@@ -3714,6 +3724,9 @@ exec_assign_value(PLpgSQL_execstate *estate,
37143724

37153725
casePLPGSQL_DTYPE_ARRAYELEM:
37163726
{
3727+
/*
3728+
* Target is an element of an array
3729+
*/
37173730
intnsubscripts;
37183731
inti;
37193732
PLpgSQL_expr*subscripts[MAXDIM];
@@ -3729,10 +3742,19 @@ exec_assign_value(PLpgSQL_execstate *estate,
37293742
coerced_value;
37303743
ArrayType*oldarrayval;
37313744
ArrayType*newarrayval;
3745+
SPITupleTable*save_eval_tuptable;
3746+
3747+
/*
3748+
* We need to do subscript evaluation, which might require
3749+
* evaluating general expressions; and the caller might have
3750+
* done that too in order to prepare the input Datum. We
3751+
* have to save and restore the caller's SPI_execute result,
3752+
* if any.
3753+
*/
3754+
save_eval_tuptable=estate->eval_tuptable;
3755+
estate->eval_tuptable=NULL;
37323756

37333757
/*
3734-
* Target is an element of an array
3735-
*
37363758
* To handle constructs like x[1][2] := something, we have to
37373759
* be prepared to deal with a chain of arrayelem datums. Chase
37383760
* back to find the base array datum, and save the subscript
@@ -3786,8 +3808,23 @@ exec_assign_value(PLpgSQL_execstate *estate,
37863808
ereport(ERROR,
37873809
(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
37883810
errmsg("array subscript in assignment must not be null")));
3811+
3812+
/*
3813+
* Clean up in case the subscript expression wasn't simple.
3814+
* We can't do exec_eval_cleanup, but we can do this much
3815+
* (which is safe because the integer subscript value is
3816+
* surely pass-by-value), and we must do it in case the
3817+
* next subscript expression isn't simple either.
3818+
*/
3819+
if (estate->eval_tuptable!=NULL)
3820+
SPI_freetuptable(estate->eval_tuptable);
3821+
estate->eval_tuptable=NULL;
37893822
}
37903823

3824+
/* Now we can restore caller's SPI_execute result if any. */
3825+
Assert(estate->eval_tuptable==NULL);
3826+
estate->eval_tuptable=save_eval_tuptable;
3827+
37913828
/* Coerce source value to match array element type. */
37923829
coerced_value=exec_simple_cast_value(value,
37933830
valtype,

‎src/test/regress/expected/plpgsql.out‎

Lines changed: 43 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3945,6 +3945,49 @@ SELECT * FROM leaker_1(true);
39453945

39463946
DROP FUNCTION leaker_1(bool);
39473947
DROP FUNCTION leaker_2(bool);
3948+
-- Test for appropriate cleanup of non-simple expression evaluations
3949+
-- (bug in all versions prior to August 2010)
3950+
CREATE FUNCTION nonsimple_expr_test() RETURNS text[] AS $$
3951+
DECLARE
3952+
arr text[];
3953+
lr text;
3954+
i integer;
3955+
BEGIN
3956+
arr := array[array['foo','bar'], array['baz', 'quux']];
3957+
lr := 'fool';
3958+
i := 1;
3959+
-- use sub-SELECTs to make expressions non-simple
3960+
arr[(SELECT i)][(SELECT i+1)] := (SELECT lr);
3961+
RETURN arr;
3962+
END;
3963+
$$ LANGUAGE plpgsql;
3964+
SELECT nonsimple_expr_test();
3965+
nonsimple_expr_test
3966+
-------------------------
3967+
{{foo,fool},{baz,quux}}
3968+
(1 row)
3969+
3970+
DROP FUNCTION nonsimple_expr_test();
3971+
CREATE FUNCTION nonsimple_expr_test() RETURNS integer AS $$
3972+
declare
3973+
i integer NOT NULL := 0;
3974+
begin
3975+
begin
3976+
i := (SELECT NULL::integer); -- should throw error
3977+
exception
3978+
WHEN OTHERS THEN
3979+
i := (SELECT 1::integer);
3980+
end;
3981+
return i;
3982+
end;
3983+
$$ LANGUAGE plpgsql;
3984+
SELECT nonsimple_expr_test();
3985+
nonsimple_expr_test
3986+
---------------------
3987+
1
3988+
(1 row)
3989+
3990+
DROP FUNCTION nonsimple_expr_test();
39483991
-- Test handling of string literals.
39493992
set standard_conforming_strings = off;
39503993
create or replace function strtest() returns text as $$

‎src/test/regress/sql/plpgsql.sql‎

Lines changed: 40 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3150,6 +3150,46 @@ SELECT * FROM leaker_1(true);
31503150
DROPFUNCTION leaker_1(bool);
31513151
DROPFUNCTION leaker_2(bool);
31523152

3153+
-- Test for appropriate cleanup of non-simple expression evaluations
3154+
-- (bug in all versions prior to August 2010)
3155+
3156+
CREATEFUNCTIONnonsimple_expr_test() RETURNStext[]AS $$
3157+
DECLARE
3158+
arrtext[];
3159+
lrtext;
3160+
iinteger;
3161+
BEGIN
3162+
arr := array[array['foo','bar'], array['baz','quux']];
3163+
lr :='fool';
3164+
i :=1;
3165+
-- use sub-SELECTs to make expressions non-simple
3166+
arr[(SELECT i)][(SELECT i+1)] := (SELECT lr);
3167+
RETURN arr;
3168+
END;
3169+
$$ LANGUAGE plpgsql;
3170+
3171+
SELECT nonsimple_expr_test();
3172+
3173+
DROPFUNCTION nonsimple_expr_test();
3174+
3175+
CREATEFUNCTIONnonsimple_expr_test() RETURNSintegerAS $$
3176+
declare
3177+
iintegerNOT NULL :=0;
3178+
begin
3179+
begin
3180+
i := (SELECTNULL::integer);-- should throw error
3181+
exception
3182+
WHEN OTHERS THEN
3183+
i := (SELECT1::integer);
3184+
end;
3185+
return i;
3186+
end;
3187+
$$ LANGUAGE plpgsql;
3188+
3189+
SELECT nonsimple_expr_test();
3190+
3191+
DROPFUNCTION nonsimple_expr_test();
3192+
31533193
-- Test handling of string literals.
31543194

31553195
set standard_conforming_strings= off;

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