From 099063340bb1f82cc3e156e5558f6c456b41bfa5 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 2 Jan 2019 16:33:48 -0500 Subject: [PATCH] Don't believe MinMaxExpr is leakproof without checking. MinMaxExpr invokes the btree comparison function for its input datatype, so it's only leakproof if that function is. Many such functions are indeed leakproof, but others are not, and we should not just assume that they are. Hence, adjust contain_leaked_vars to verify the leakproofness of the referenced function explicitly. I didn't add a regression test because it would need to depend on some particular comparison function being leaky, and that's a moving target, per discussion. This has been wrong all along, so back-patch to supported branches. Discussion: https://postgr.es/m/31042.1546194242@sss.pgh.pa.us --- src/backend/optimizer/util/clauses.c | 31 +++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c index 21bf5dea9c..df56569c50 100644 --- a/src/backend/optimizer/util/clauses.c +++ b/src/backend/optimizer/util/clauses.c @@ -1579,7 +1579,6 @@ contain_leaked_vars_walker(Node *node, void *context) case T_CaseExpr: case T_CaseTestExpr: case T_RowExpr: - case T_MinMaxExpr: case T_SQLValueFunction: case T_NullTest: case T_BooleanTest: @@ -1636,6 +1635,36 @@ contain_leaked_vars_walker(Node *node, void *context) } break; + case T_MinMaxExpr: + { + /* + * MinMaxExpr is leakproof if the comparison function it calls + * is leakproof. + */ + MinMaxExpr *minmaxexpr = (MinMaxExpr *) node; + TypeCacheEntry *typentry; + bool leakproof; + + /* Look up the btree comparison function for the datatype */ + typentry = lookup_type_cache(minmaxexpr->minmaxtype, + TYPECACHE_CMP_PROC); + if (OidIsValid(typentry->cmp_proc)) + leakproof = get_func_leakproof(typentry->cmp_proc); + else + { + /* + * The executor will throw an error, but here we just + * treat the missing function as leaky. + */ + leakproof = false; + } + + if (!leakproof && + contain_var_clause((Node *) minmaxexpr->args)) + return true; + } + break; + case T_CurrentOfExpr: /*