From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757124Ab3CYB11 (ORCPT ); Sun, 24 Mar 2013 21:27:27 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34026 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756120Ab3CYBQH (ORCPT ); Sun, 24 Mar 2013 21:16:07 -0400 Message-Id: <20130325010530.122444643@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 25 Mar 2013 01:06:23 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, "Steven Rostedt (Red Hat)" Subject: [ 059/104] tracing: Protect tracer flags with trace_types_lock Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In-Reply-To: <20130325010524.240972766@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:f137:78a:b654:affb X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Steven Rostedt (Red Hat)" commit 69d34da2984c95b33ea21518227e1f9470f11d95 upstream. Seems that the tracer flags have never been protected from synchronous writes. Luckily, admins don't usually modify the tracing flags via two different tasks. But if scripts were to be used to modify them, then they could get corrupted. Move the trace_types_lock that protects against tracers changing to also protect the flags being set. Signed-off-by: Steven Rostedt [bwh: Backported to 3.2: also move failure return in tracing_trace_options_write() after unlocking] Signed-off-by: Ben Hutchings --- --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2661,7 +2661,7 @@ tracing_trace_options_write(struct file char buf[64]; char *cmp; int neg = 0; - int ret; + int ret = 0; int i; if (cnt >= sizeof(buf)) @@ -2678,6 +2678,8 @@ tracing_trace_options_write(struct file cmp += 2; } + mutex_lock(&trace_types_lock); + for (i = 0; trace_options[i]; i++) { if (strcmp(cmp, trace_options[i]) == 0) { set_tracer_flags(1 << i, !neg); @@ -2686,13 +2688,13 @@ tracing_trace_options_write(struct file } /* If no option could be set, test the specific tracer options */ - if (!trace_options[i]) { - mutex_lock(&trace_types_lock); + if (!trace_options[i]) ret = set_tracer_option(current_trace, cmp, neg); - mutex_unlock(&trace_types_lock); - if (ret) - return ret; - } + + mutex_unlock(&trace_types_lock); + + if (ret) + return ret; *ppos += cnt; @@ -4379,7 +4381,10 @@ trace_options_core_write(struct file *fi if (val != 0 && val != 1) return -EINVAL; + + mutex_lock(&trace_types_lock); set_tracer_flags(1 << index, val); + mutex_unlock(&trace_types_lock); *ppos += cnt;