tracing: Protect tracer flags with trace_types_lock
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.
Cc: stable@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 53df283..00daf5f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2916,6 +2916,8 @@
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);
@@ -2924,11 +2926,10 @@
}
/* 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);
- }
+
+ mutex_unlock(&trace_types_lock);
return ret;
}
@@ -4781,7 +4782,10 @@
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;
