From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Steven Rostedt , Lingzhu Xiang , CAI Qian Subject: [ 39/56] tracing: Protect tracer flags with trace_types_lock Date: Tue, 2 Apr 2013 15:50:06 -0700 Message-Id: <20130402224716.401935996@linuxfoundation.org> In-Reply-To: <20130402224711.840825715@linuxfoundation.org> References: <20130402224711.840825715@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.0-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. [Backported for 3.4, 3.0-stable. Moved return to after unlock.] Signed-off-by: Steven Rostedt Signed-off-by: Lingzhu Xiang Reviewed-by: CAI Qian Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2552,7 +2552,7 @@ 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)) @@ -2569,6 +2569,8 @@ 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); @@ -2577,13 +2579,13 @@ 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; @@ -4180,7 +4182,10 @@ 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;