From b26d8fda6535799be6eee1e93a8f11756b11af95 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 31 May 2011 17:53:55 -0400
Subject: [PATCH] Protect GIST logic that assumes penalty values can't be
negative.
Apparently sane-looking penalty code might return small negative values,
for example because of roundoff error. This will confuse places like
gistchoose(). Prevent problems by clamping negative penalty values to
zero. (Just to be really sure, I also made it force NaNs to zero.)
Back-patch to all supported branches.
Alexander Korotkov
---
doc/src/sgml/gist.sgml | 2 ++
src/backend/access/gist/gistutil.c | 14 +++++++++++---
2 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/doc/src/sgml/gist.sgml b/doc/src/sgml/gist.sgml
index 5757ce8002..65084842d4 100644
--- a/doc/src/sgml/gist.sgml
+++ b/doc/src/sgml/gist.sgml
@@ -374,6 +374,8 @@ my_decompress(PG_FUNCTION_ARGS)
Returns a value indicating the <quote>cost</quote> of inserting the new
entry into a particular branch of the tree. Items will be inserted
down the path of least <function>penalty</function> in the tree.
+ Values returned by <function>penalty</function> should be non-negative.
+ If a negative value is returned, it will be treated as zero.
</para>
<para>
diff --git a/src/backend/access/gist/gistutil.c b/src/backend/access/gist/gistutil.c
index a23047642f..48c44157be 100644
--- a/src/backend/access/gist/gistutil.c
+++ b/src/backend/access/gist/gistutil.c
@@ -13,6 +13,8 @@
*/
#include "postgres.h"
+#include <math.h>
+
#include "access/gist_private.h"
#include "access/reloptions.h"
#include "storage/freespace.h"
@@ -532,16 +534,22 @@ gistpenalty(GISTSTATE *giststate, int attno,
{
float penalty = 0.0;
- if (giststate->penaltyFn[attno].fn_strict == FALSE || (isNullOrig == FALSE && isNullAdd == FALSE))
+ if (giststate->penaltyFn[attno].fn_strict == FALSE ||
+ (isNullOrig == FALSE && isNullAdd == FALSE))
+ {
FunctionCall3(&giststate->penaltyFn[attno],
PointerGetDatum(orig),
PointerGetDatum(add),
PointerGetDatum(&penalty));
+ /* disallow negative or NaN penalty */
+ if (isnan(penalty) || penalty < 0.0)
+ penalty = 0.0;
+ }
else if (isNullOrig && isNullAdd)
penalty = 0.0;
else
- penalty = 1e10; /* try to prevent to mix null and non-null
- * value */
+ penalty = 1e10; /* try to prevent mixing null and non-null
+ * values */
return penalty;
}
--
2.49.0