From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753925AbdJIC7f (ORCPT ); Sun, 8 Oct 2017 22:59:35 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:36367 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751172AbdJIC7e (ORCPT ); Sun, 8 Oct 2017 22:59:34 -0400 X-ME-Sender: X-Sasl-enc: 9UKduc8VpRrEOaP2n036VzjZg+A7B0s1uYXVMULQ38Mw 1507517972 From: "Tobin C. Harding" To: kernel-hardening@lists.openwall.com Cc: "Tobin C. Harding" , linux-kernel@vger.kernel.org Subject: [PATCH] lib/vsprintf: add default case to 'i' specifier Date: Mon, 9 Oct 2017 13:59:05 +1100 Message-Id: <1507517945-27155-1-git-send-email-me@tobin.cc> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org %pi leaks kernel addresses if incorrectly specified. Currently the printk specifier %pi (%pI) contains a switch statement without a default clause. The %pi specifier requires a subsequent character (4, 6, or S) controlling the output. If the specifier is incomplete the switch statement will fall through and print the variable argument address in hex instead of the value of the argument (as an IP address). If uncaught this leaks kernel addresses into dmesg. We can return an error string to make the bug visible and stop addresses leaking. Add a default clause returning an error string, stops leaking addresses and makes the buggy code Signed-off-by: Tobin C. Harding --- lib/vsprintf.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 86c3385b9eb3..155702f05b14 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1775,6 +1775,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, default: return string(buf, end, "(invalid address)", spec); }} + default: + return string(buf, end, "(invalid specifier, form: %pi4)", spec); } break; case 'E': -- 2.7.4