From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id E9E247D082 for ; Mon, 8 Oct 2018 11:06:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727526AbeJHSQS (ORCPT ); Mon, 8 Oct 2018 14:16:18 -0400 Received: from xavier.telenet-ops.be ([195.130.132.52]:52842 "EHLO xavier.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727360AbeJHSQS (ORCPT ); Mon, 8 Oct 2018 14:16:18 -0400 Received: from ramsan.of.borg ([84.194.111.163]) by xavier.telenet-ops.be with bizsmtp id kz561y0023XaVaC01z56XV; Mon, 08 Oct 2018 13:05:06 +0200 Received: from rox.of.borg ([192.168.97.57]) by ramsan.of.borg with esmtp (Exim 4.86_2) (envelope-from ) id 1g9TLV-000517-VB; Mon, 08 Oct 2018 13:05:05 +0200 Received: from geert by rox.of.borg with local (Exim 4.90_1) (envelope-from ) id 1g9TLV-0006dR-U3; Mon, 08 Oct 2018 13:05:05 +0200 From: Geert Uytterhoeven To: Petr Mladek , Andy Shevchenko , "Tobin C . Harding" , Andrew Morton , Jonathan Corbet Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH 3/3] lib/vsprintf: Hash printed address for netdev bits fallback Date: Mon, 8 Oct 2018 13:05:04 +0200 Message-Id: <20181008110504.25449-4-geert+renesas@glider.be> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181008110504.25449-1-geert+renesas@glider.be> References: <20181008110504.25449-1-geert+renesas@glider.be> Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org The handler for "%pN" falls back to printing the raw pointer value when using a different format than the (sole supported) special format "%pNF", potentially leaking sensitive information regarding the kernel layout in memory. Avoid this leak by printing the hashed address instead. Note that there are no in-tree users of the fallback. Fixes: ad67b74d2469d9b8 ("printk: hash addresses printed with %p") Signed-off-by: Geert Uytterhoeven --- lib/vsprintf.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 1fb36260a44289e8..a3dc15c89c217b79 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -1424,7 +1424,8 @@ char *restricted_pointer(char *buf, char *end, const void *ptr, } static noinline_for_stack -char *netdev_bits(char *buf, char *end, const void *addr, const char *fmt) +char *netdev_bits(char *buf, char *end, const void *addr, + struct printf_spec spec, const char *fmt) { unsigned long long num; int size; @@ -1435,9 +1436,7 @@ char *netdev_bits(char *buf, char *end, const void *addr, const char *fmt) size = sizeof(netdev_features_t); break; default: - num = (unsigned long)addr; - size = sizeof(unsigned long); - break; + return ptr_to_id(buf, end, addr, spec); } return special_hex_number(buf, end, num, size); @@ -1952,7 +1951,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, break; return restricted_pointer(buf, end, ptr, spec); case 'N': - return netdev_bits(buf, end, ptr, fmt); + return netdev_bits(buf, end, ptr, spec, fmt); case 'a': return address_val(buf, end, ptr, fmt); case 'd': -- 2.17.1