Remove typmod checking from the recent security-related patches. It turns

out that ExecEvalVar and friends don't necessarily have access to a tuple
descriptor with correct typmod: it definitely can contain -1, and possibly
might contain other values that are different from the Var's value.
Arguably this should be cleaned up someday, but it's not a simple change,
and in any case typmod discrepancies don't pose a security hazard.
Per reports from numerous people :-(

I'm not entirely sure whether the failure can occur in 8.0 --- the simple
test cases reported so far don't trigger it there.  But back-patch the
change all the way anyway.

diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index be3e1c12188d56ce669fce34a1e66267da072fb8..865b8a6ab65b60bd0362e61dc876faa87ad7af5b 100644 (file)
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.171.4.3 2007/02/02 00:08:01 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/executor/execQual.c,v 1.171.4.4 2007/02/06 17:35:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -502,8 +502,11 @@ ExecEvalVar(ExprState *exprstate, ExprContext *econtext,
                 * Note: we allow a reference to a dropped attribute, and force a
                 * NULL result.  This path is not fast.
                 *
-                * Note: we check typmod, but allow the case that the Var has
-                * unspecified typmod while the column has a specific typmod.
+                * Note: ideally we'd check typmod as well as typid, but that seems
+                * impractical at the moment: in many cases the tupdesc will have
+                * been generated by ExecTypeFromTL(), and that can't guarantee to
+                * generate an accurate typmod in all cases, because some expression
+                * node types don't carry typmod.
                 */
                if (attnum > 0)
                {
@@ -529,9 +532,7 @@ ExecEvalVar(ExprState *exprstate, ExprContext *econtext,
                                return (Datum) 0;
                        }
 
-                       if (variable->vartype != attr->atttypid ||
-                               (variable->vartypmod != attr->atttypmod &&
-                                variable->vartypmod != -1))
+                       if (variable->vartype != attr->atttypid)
                                ereport(ERROR,
                                                (errmsg("attribute %d has wrong type", attnum),
                                                 errdetail("Table has type %s, but query expects %s.",
@@ -2856,9 +2857,8 @@ ExecEvalFieldSelect(FieldSelectState *fstate,
        }
 
        /* Check for type mismatch --- possible after ALTER COLUMN TYPE? */
-       if (fselect->resulttype != attr->atttypid ||
-               (fselect->resulttypmod != attr->atttypmod &&
-                fselect->resulttypmod != -1))
+       /* As in ExecEvalVar, we should but can't check typmod */
+       if (fselect->resulttype != attr->atttypid)
                ereport(ERROR,
                                (errmsg("attribute %d has wrong type", fieldnum),
                                 errdetail("Table has type %s, but query expects %s.",