Fix SPI_getvalue and SPI_getbinval to range-check the given attribute number

according to the TupleDesc's natts, not the number of physical columns in the
tuple.  The previous coding would do the wrong thing in cases where natts is
different from the tuple's column count: either incorrectly report error when
it should just treat the column as null, or actually crash due to indexing off
the end of the TupleDesc's attribute array.  (The second case is probably not
possible in modern PG versions, due to more careful handling of inheritance
cases than we once had.  But it's still a clear lack of robustness here.)

The incorrect error indication is ignored by all callers within the core PG
distribution, so this bug has no symptoms visible within the core code, but
it might well be an issue for add-on packages.  So patch all the way back.

diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index 5999418ccc176f87348b584a6568717c67423826..cb1a33204924e77ff60c2845b2ddc873934fdd49 100644 (file)
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.144.2.3 2007/08/15 19:16:04 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/executor/spi.c,v 1.144.2.4 2008/10/16 13:23:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -642,7 +642,7 @@ SPI_getvalue(HeapTuple tuple, TupleDesc tupdesc, int fnumber)
 
        SPI_result = 0;
 
-       if (fnumber > tuple->t_data->t_natts || fnumber == 0 ||
+       if (fnumber > tupdesc->natts || fnumber == 0 ||
                fnumber <= FirstLowInvalidHeapAttributeNumber)
        {
                SPI_result = SPI_ERROR_NOATTRIBUTE;
@@ -684,7 +684,7 @@ SPI_getbinval(HeapTuple tuple, TupleDesc tupdesc, int fnumber, bool *isnull)
 {
        SPI_result = 0;
 
-       if (fnumber > tuple->t_data->t_natts || fnumber == 0 ||
+       if (fnumber > tupdesc->natts || fnumber == 0 ||
                fnumber <= FirstLowInvalidHeapAttributeNumber)
        {
                SPI_result = SPI_ERROR_NOATTRIBUTE;