From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1EBC4C282DA for ; Wed, 17 Apr 2019 11:55:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EDB0F20835 for ; Wed, 17 Apr 2019 11:54:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732178AbfDQLy6 (ORCPT ); Wed, 17 Apr 2019 07:54:58 -0400 Received: from mx2.suse.de ([195.135.220.15]:43668 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732059AbfDQLyQ (ORCPT ); Wed, 17 Apr 2019 07:54:16 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id F34A9AD76; Wed, 17 Apr 2019 11:54:14 +0000 (UTC) From: Petr Mladek To: Andy Shevchenko , Rasmus Villemoes Cc: Linus Torvalds , "Tobin C . Harding" , Joe Perches , Andrew Morton , Michal Hocko , Sergey Senozhatsky , Steven Rostedt , Sergey Senozhatsky , linux-kernel@vger.kernel.org, Petr Mladek , Kees Cook Subject: [PATCH v7 02/10] vsprintf: Consistent %pK handling for kptr_restrict == 0 Date: Wed, 17 Apr 2019 13:53:42 +0200 Message-Id: <20190417115350.20479-3-pmladek@suse.com> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190417115350.20479-1-pmladek@suse.com> References: <20190417115350.20479-1-pmladek@suse.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org restricted_pointer() pretends that it prints the address when kptr_restrict is set to zero. But it is never called in this situation. Instead, pointer() falls back to ptr_to_id() and hashes the pointer. This patch removes the potential confusion. klp_restrict is checked only in restricted_pointer(). It actually fixes a small race when the address might get printed unhashed: CPU0 CPU1 pointer() if (!kptr_restrict) /* for example set to 2 */ restricted_pointer() /* echo 0 >/proc/sys/kernel/kptr_restrict */ proc_dointvec_minmax_sysadmin() klpr_restrict = 0; switch(kptr_restrict) case 0: break: number() Fixes: commit ef0010a30935de4e0211 ("vsprintf: don't use 'restricted_pointer()' when not restricting") Cc: Linus Torvalds Cc: Tobin Harding Cc: Kees Cook Signed-off-by: Petr Mladek Reviewed-by: Andy Shevchenko --- lib/vsprintf.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index eb7b4a06e1f0..2af48948a973 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -725,8 +725,8 @@ char *restricted_pointer(char *buf, char *end, const void *ptr, { switch (kptr_restrict) { case 0: - /* Always print %pK values */ - break; + /* Handle as %p, hash and do _not_ leak addresses. */ + return ptr_to_id(buf, end, ptr, spec); case 1: { const struct cred *cred; @@ -2041,8 +2041,6 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, return buf; } case 'K': - if (!kptr_restrict) - break; return restricted_pointer(buf, end, ptr, spec); case 'N': return netdev_bits(buf, end, ptr, spec, fmt); -- 2.16.4