From 2f6b6e28ca9af9c1f745efa9277e3e7c9ad64883 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Thu, 14 Mar 2013 13:50:56 -0400 Subject: [PATCH] tracing: Protect tracer flags with trace_types_lock 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(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 681a759..a786b6a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -2768,7 +2768,7 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf, char buf[64]; char *cmp; int neg = 0; - int ret; + int ret = 0; int i; if (cnt >= sizeof(buf)) @@ -2785,6 +2785,8 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf, 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); @@ -2793,13 +2795,13 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf, } /* 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; @@ -4486,7 +4488,10 @@ trace_options_core_write(struct file *filp, const char __user *ubuf, size_t cnt, 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; -- 2.7.4