privilege: fix grant for global level grant(cherry-pick from 4.0) (#3…

…0161)

close #29675

planner/core/planbuilder.go

@@ -2271,7 +2271,8 @@ func collectVisitInfoFromRevokeStmt(sctx sessionctx.Context, vi []visitInfo, stm
 	// and you must have the privileges that you are granting.
 	dbName := stmt.Level.DBName
 	tableName := stmt.Level.TableName
-	if dbName == "" {
+	// do not add dbName to the visitInfo of a *.* grant.
+	if dbName == "" && stmt.Level.Level != ast.GrantLevelGlobal {
 		dbName = sctx.GetSessionVars().CurrentDB
 	}
 	vi = appendVisitInfo(vi, mysql.GrantPriv, dbName, tableName, "", nil)
@@ -2304,7 +2305,8 @@ func collectVisitInfoFromGrantStmt(sctx sessionctx.Context, vi []visitInfo, stmt
 	// and you must have the privileges that you are granting.
 	dbName := stmt.Level.DBName
 	tableName := stmt.Level.TableName
-	if dbName == "" {
+	// do not add dbName to the visitInfo of a *.* grant.
+	if dbName == "" && stmt.Level.Level != ast.GrantLevelGlobal {
 		dbName = sctx.GetSessionVars().CurrentDB
 	}
 	vi = appendVisitInfo(vi, mysql.GrantPriv, dbName, tableName, "", nil)

privilege/privileges/privileges_test.go

@@ -804,6 +804,17 @@ func (s *testPrivilegeSuite) TestCheckAuthenticate(c *C) {
 	mustExec(c, se1, "drop user 'r3@example.com'@'localhost'")
 }
 
+func (s *testPrivilegeSuite) TestGlobalGrantInfoDB(c *C) {
+	se := newSession(c, s.store, "INFORMATION_SCHEMA")
+	//mustExec(c, se, "USE information_schema'")
+	mustExec(c, se, "CREATE USER 'global'")
+	// can be executed in information schema for *.*
+	_, e := se.Execute(context.Background(), "GRANT all privileges ON *.* TO 'global'")
+	c.Assert(e, IsNil)
+	_, e = se.Execute(context.Background(), "REVOKE all privileges on *.* FROM 'global'")
+	c.Assert(e, IsNil)
+}
+
 func (s *testPrivilegeSuite) TestUseDB(c *C) {
 
 	se := newSession(c, s.store, s.dbName)