sysvar: fix inconsistency in setting password validation sysvars (#39584

)

ref #38928

sessionctx/variable/sysvar.go

@@ -520,7 +520,10 @@ var defaultSysVars = []*SysVar{
 				return "", err
 			}
 			if minLength := numberCount + specialCharCount + 2*int32(mixedCaseCount); length < minLength {
-				PasswordValidationLength.Store(minLength)
+				err = updatePasswordValidationLength(vars, minLength)
+				if err != nil {
+					return "", err
+				}
 			}
 			return normalizedValue, nil
 		},
@@ -539,7 +542,10 @@ var defaultSysVars = []*SysVar{
 				return "", err
 			}
 			if minLength := int32(numberCount) + specialCharCount + 2*mixedCaseCount; length < minLength {
-				PasswordValidationLength.Store(minLength)
+				err = updatePasswordValidationLength(vars, minLength)
+				if err != nil {
+					return "", err
+				}
 			}
 			return normalizedValue, nil
 		},
@@ -558,7 +564,10 @@ var defaultSysVars = []*SysVar{
 				return "", err
 			}
 			if minLength := numberCount + int32(specialCharCount) + 2*mixedCaseCount; length < minLength {
-				PasswordValidationLength.Store(minLength)
+				err = updatePasswordValidationLength(vars, minLength)
+				if err != nil {
+					return "", err
+				}
 			}
 			return normalizedValue, nil
 		},

sessionctx/variable/varsutil.go

@@ -15,6 +15,7 @@
 package variable
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"strconv"
@@ -531,6 +532,15 @@ func collectAllowFuncName4ExpressionIndex() string {
 	return strings.Join(str, ", ")
 }
 
+func updatePasswordValidationLength(s *SessionVars, length int32) error {
+	err := s.GlobalVarsAccessor.SetGlobalSysVarOnly(context.Background(), ValidatePasswordLength, strconv.FormatInt(int64(length), 10))
+	if err != nil {
+		return err
+	}
+	PasswordValidationLength.Store(length)
+	return nil
+}
+
 // GAFunction4ExpressionIndex stores functions GA for expression index.
 var GAFunction4ExpressionIndex = map[string]struct{}{
 	ast.Lower:      {},