From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 6 Feb 2007 17:35:41 +0000 (+0000)
Subject: Remove typmod checking from the recent security-related patches.  It turns
X-Git-Tag: REL8_0_12~3
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=122680c51443b66fd9fc8687881ad571248516fa;p=thirdparty%2Fpostgresql.git

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 be3e1c12188..865b8a6ab65 100644
--- 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.",