From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938368AbdLSD2a (ORCPT ); Mon, 18 Dec 2017 22:28:30 -0500 Received: from out3-smtp.messagingengine.com ([66.111.4.27]:34111 "EHLO out3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934072AbdLSD22 (ORCPT ); Mon, 18 Dec 2017 22:28:28 -0500 X-ME-Sender: From: "Tobin C. Harding" To: kernel-hardening@lists.openwall.com Cc: "Tobin C. Harding" , Steven Rostedt , Tycho Andersen , Linus Torvalds , Kees Cook , Andrew Morton , Daniel Borkmann , Masahiro Yamada , Alexei Starovoitov , linux-kernel@vger.kernel.org, Network Development Subject: [PATCH v2 0/3] kallsyms: don't leak address Date: Tue, 19 Dec 2017 14:28:11 +1100 Message-Id: <1513654094-16832-1-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 This set plugs a kernel address leak that occurs if kallsyms symbol look up fails. This set was prompted by a leaking address found using scripts/leaking_addresses.pl on a PowerPC machine in the wild. $ perl scripts/leaking_addresses.pl [address sanitized] ... /proc/8025/task/8025/stack: [<0000000000000000>] 0xc0000001XXXXXXXX $ uname -r 4.4.0-79-powerpc64-smp Patch set does not change behaviour when KALLSYMS is not defined (suggested by Linus). Comments on version 1 indicated that current behaviour may be useful for debugging. This version adds a kernel command-line parameter in order to be able to preserve current behaviour (print raw address if kallsyms symbol look up fails). (Command-line parameter suggested by Steve.) New command-line parameter is documented only in the kernel-doc for kallsyms functions sprint_symbol() and sprint_symbol_no_offset(). Is this sufficient? Perhaps an entry in printk-formats.txt also? Patch 1 - return error code if symbol look up fails unless new command-line parameter 'insecure_print_all_symbols' is enabled. Patch 2 - print to buffer if symbol look up returns an error. Patch 3 - maintain current behaviour in ftrace. thanks, Tobin. v2: - Add kernel command-line parameter. - Remove unnecessary function. - Fix broken ftrace code (and actually build and test ftrace code). Patch 1 and 2 tested. Patch 3 (ftrace) tested but not all code paths executed (discussed with Steve in another thread). Tobin C. Harding (3): kallsyms: don't leak address when symbol not found vsprintf: print if symbol not found trace: print address if symbol not found kernel/kallsyms.c | 31 +++++++++++++++++++++++++------ kernel/trace/trace.h | 24 ++++++++++++++++++++++++ kernel/trace/trace_events_hist.c | 6 +++--- kernel/trace/trace_output.c | 2 +- lib/vsprintf.c | 11 ++++++++--- 5 files changed, 61 insertions(+), 13 deletions(-) -- 2.7.4