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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2013-03-14 13:50:56 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-04-05 10:16:52 -0700
commitb9736c0eed0bfe68c89a269c89c3483d39ea1c83 (patch)
tree222922f576193d75c835f8f097285ce5e91eab16
parent503f4bdcc078e7abee273a85ce322de81b18a224 (diff)
downloadlinux-linaro-stable-b9736c0eed0bfe68c89a269c89c3483d39ea1c83.tar.gz
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 <rostedt@goodmis.org> Signed-off-by: Lingzhu Xiang <lxiang@redhat.com> Reviewed-by: CAI Qian <caiqian@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--kernel/trace/trace.c19
1 files changed, 12 insertions, 7 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 97bf54027b09..420d49ef3c9f 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2552,7 +2552,7 @@ 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))
@@ -2569,6 +2569,8 @@ 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);
@@ -2577,13 +2579,13 @@ 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;
@@ -4180,7 +4182,10 @@ 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;