From a034418cfc85fffa300d4d44792561c09e76f68b Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 5 Aug 2019 11:20:21 -0400
Subject: [PATCH] Fix choice of comparison operators for cross-type hashed
subplans.
Commit bf6c614a2 rearranged the lookup of the comparison operators
needed in a hashed subplan, and in so doing, broke the cross-type
case: it caused the original LHS-vs-RHS operator to be used to compare
hash table entries too (which of course are all of the RHS type).
This leads to C functions being passed a Datum that is not of the
type they expect, with the usual hazards of crashes and unauthorized
server memory disclosure.
For the set of hashable cross-type operators present in v11 core
Postgres, this bug is nearly harmless on 64-bit machines, which
may explain why it escaped earlier detection. But it is a live
security hazard on 32-bit machines; and of course there may be
extensions that add more hashable cross-type operators, which
would increase the risk.
Reported by Andreas Seltenreich. Back-patch to v11 where the
problem came in.
Security: CVE-2019-10209
---
src/backend/executor/nodeSubplan.c | 15 ++++++++++-----
src/test/regress/expected/subselect.out | 24 ++++++++++++++++++++++++
src/test/regress/sql/subselect.sql | 10 ++++++++++
3 files changed, 44 insertions(+), 5 deletions(-)
diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c
index 9564d54ed4c..35e45671d4c 100644
--- a/src/backend/executor/nodeSubplan.c
+++ b/src/backend/executor/nodeSubplan.c
@@ -855,6 +855,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
i;
TupleDesc tupDescLeft;
TupleDesc tupDescRight;
+ Oid *cross_eq_funcoids;
TupleTableSlot *slot;
List *oplist,
*lefttlist,
@@ -917,6 +918,9 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
sstate->tab_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
sstate->lhs_hash_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
sstate->cur_eq_funcs = (FmgrInfo *) palloc(ncols * sizeof(FmgrInfo));
+ /* we'll need the cross-type equality fns below, but not in sstate */
+ cross_eq_funcoids = (Oid *) palloc(ncols * sizeof(Oid));
+
i = 1;
foreach(l, oplist)
{
@@ -946,7 +950,7 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
righttlist = lappend(righttlist, tle);
/* Lookup the equality function (potentially cross-type) */
- sstate->tab_eq_funcoids[i - 1] = opexpr->opfuncid;
+ cross_eq_funcoids[i - 1] = opexpr->opfuncid;
fmgr_info(opexpr->opfuncid, &sstate->cur_eq_funcs[i - 1]);
fmgr_info_set_expr((Node *) opexpr, &sstate->cur_eq_funcs[i - 1]);
@@ -955,7 +959,9 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
NULL, &rhs_eq_oper))
elog(ERROR, "could not find compatible hash operator for operator %u",
opexpr->opno);
- fmgr_info(get_opcode(rhs_eq_oper), &sstate->tab_eq_funcs[i - 1]);
+ sstate->tab_eq_funcoids[i - 1] = get_opcode(rhs_eq_oper);
+ fmgr_info(sstate->tab_eq_funcoids[i - 1],
+ &sstate->tab_eq_funcs[i - 1]);
/* Lookup the associated hash functions */
if (!get_op_hash_functions(opexpr->opno,
@@ -994,14 +1000,13 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent)
/*
* Create comparator for lookups of rows in the table (potentially
- * across-type comparison).
+ * cross-type comparisons).
*/
sstate->cur_eq_comp = ExecBuildGroupingEqual(tupDescLeft, tupDescRight,
ncols,
sstate->keyColIdx,
- sstate->tab_eq_funcoids,
+ cross_eq_funcoids,
parent);
-
}
return sstate;
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index 588d0695892..a288c6d33b8 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -745,6 +745,30 @@ select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
1 |
(2 rows)
+--
+-- Another test case for cross-type hashed subplans: comparison of
+-- inner-side values must be done with appropriate operator
+--
+explain (verbose, costs off)
+select 'foo'::text in (select 'bar'::name union all select 'bar'::name);
+ QUERY PLAN
+-------------------------------------
+ Result
+ Output: (hashed SubPlan 1)
+ SubPlan 1
+ -> Append
+ -> Result
+ Output: 'bar'::name
+ -> Result
+ Output: 'bar'::name
+(8 rows)
+
+select 'foo'::text in (select 'bar'::name union all select 'bar'::name);
+ ?column?
+----------
+ f
+(1 row)
+
--
-- Test case for premature memory release during hashing of subplan output
--
diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index 843f511b3dc..eafd927e828 100644
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -435,6 +435,16 @@ insert into inner_7597 values(0, null);
select * from outer_7597 where (f1, f2) not in (select * from inner_7597);
+--
+-- Another test case for cross-type hashed subplans: comparison of
+-- inner-side values must be done with appropriate operator
+--
+
+explain (verbose, costs off)
+select 'foo'::text in (select 'bar'::name union all select 'bar'::name);
+
+select 'foo'::text in (select 'bar'::name union all select 'bar'::name);
+
--
-- Test case for premature memory release during hashing of subplan output
--
--
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