diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index 54cef70..7f1ead2 100644
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -466,6 +466,16 @@
 		goto failed;
 	}
 
+	if (!c->double_hash && c->fmt_version >= 5) {
+		err = 16;
+		goto failed;
+	}
+
+	if (c->encrypted && c->fmt_version < 5) {
+		err = 17;
+		goto failed;
+	}
+
 	return 0;
 
 failed:
@@ -624,6 +634,13 @@
 	c->double_hash = !!(sup_flags & UBIFS_FLG_DOUBLE_HASH);
 	c->encrypted = !!(sup_flags & UBIFS_FLG_ENCRYPTION);
 
+	if ((sup_flags & ~UBIFS_FLG_MASK) != 0) {
+		ubifs_err(c, "Unknown feature flags found: %#x",
+			  sup_flags & ~UBIFS_FLG_MASK);
+		err = -EINVAL;
+		goto out;
+	}
+
 #ifndef CONFIG_UBIFS_FS_ENCRYPTION
 	if (c->encrypted) {
 		ubifs_err(c, "file system contains encrypted files but UBIFS"