diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 0e04b57..f7741ce 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -584,8 +584,10 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 			       SMB2_MAX_BUFFER_SIZE);
 	server->max_read = le32_to_cpu(rsp->MaxReadSize);
 	server->max_write = le32_to_cpu(rsp->MaxWriteSize);
-	/* BB Do we need to validate the SecurityMode? */
 	server->sec_mode = le16_to_cpu(rsp->SecurityMode);
+	if ((server->sec_mode & SMB2_SEC_MODE_FLAGS_ALL) != server->sec_mode)
+		cifs_dbg(FYI, "Server returned unexpected security mode 0x%x\n",
+				server->sec_mode);
 	server->capabilities = le32_to_cpu(rsp->Capabilities);
 	/* Internal types */
 	server->capabilities |= SMB2_NT_FIND | SMB2_LARGE_FILES;