At Mon, 02 Nov 2020 10:36:10 +0900 (JST), Kyotaro Horiguchi
<[email protected]> wrote in
> At Sat, 31 Oct 2020 11:49:07 -0300, Ranier Vilela <[email protected]> wrote
> in
> > Per Coverity.
> >
> > make_ruledef function can dereference a NULL pointer (actions),
> > if "ev_qual" is provided and "actions" does not exist.
> >
> > The comment there is contradictory: " /* these could be nulls */ "
> > Because if "ev_qual" is not null, "actions" cannot be either.
> >
> > Solution proposed merely as a learning experience.
>
> We cannot reach there with ev_action == NULL since it comes from a
> non-nullable column. Since most of the other columns has an assertion
> that !isnull, I think we should do the same thing for ev_action (and
> ev_qual). SPI_getvalue() returns C-NULL for SQL-NULL (or for some
> other unexpected situations.).
The following code is found there, since 1998. (15cb32d93e)
> /* If the rule has an event qualification, add it */
> if (ev_qual == NULL)
> ev_qual = "";
The problem code here was written as the follows.
+ fno = SPI_fnumber(rulettc, "is_instead");
+ is_instead = (bool)SPI_getbinval(ruletup, rulettc, fno, &isnull);
+
+ fno = SPI_fnumber(rulettc, "ev_qual");
+ ev_qual = SPI_getvalue(ruletup, rulettc, fno);
+ if (isnull) ev_qual = NULL;
+
+ fno = SPI_fnumber(rulettc, "ev_action");
+ ev_action = SPI_getvalue(ruletup, rulettc, fno);
+ if (isnull) ev_action = NULL;
+ if (ev_action != NULL) {
+ actions = (List *)stringToNode(ev_action);
+ }
I'm not sure what the code means by just reading there but at least it
seems impossible for the current code to return NULL for legit values.
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 6c656586e8..ab4f102e9b 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -4766,12 +4766,13 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
/* these could be nulls */
fno = SPI_fnumber(rulettc, "ev_qual");
ev_qual = SPI_getvalue(ruletup, rulettc, fno);
+ Assert(ev_qual != NULL);
fno = SPI_fnumber(rulettc, "ev_action");
ev_action = SPI_getvalue(ruletup, rulettc, fno);
- if (ev_action != NULL)
- actions = (List *) stringToNode(ev_action);
-
+ Assert(ev_action != NULL);
+ actions = (List *) stringToNode(ev_action);
+
ev_relation = table_open(ev_class, AccessShareLock);
/*
@@ -4819,9 +4820,6 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
generate_relation_name(ev_class, NIL) :
generate_qualified_relation_name(ev_class));
- /* If the rule has an event qualification, add it */
- if (ev_qual == NULL)
- ev_qual = "";
if (strlen(ev_qual) > 0 && strcmp(ev_qual, "<>") != 0)
{
Node *qual;
