This patch adds a create_mostly_valid_global_event case to the
perf_event_open() code.
Without this patch it is extremely unlikely that a global
(not per-process) event would be randomly created.
Most users will not notice a change, as you can only create global events
as root or else if /proc/sys/kernel/perf_event_paranoid is set to < 1
(the default is 1).
With this change some of the more obscure event types such as uncore,
northbridge, and RAPL power events are occasionally properly created.
Signed-off-by: Vince Weaver <vincent.weaver@xxxxxxxxx>
diff --git a/fuzzer/trinity_files/perf_event_open.c b/fuzzer/trinity_files/perf_event_open.c
index c4ccafd..7c20350 100644
--- a/fuzzer/trinity_files/perf_event_open.c
+++ b/fuzzer/trinity_files/perf_event_open.c
@@ -1089,6 +1089,36 @@ static void create_mostly_valid_sampling_event(struct perf_event_attr *attr,
}
+
+/* Creates a global event: one that is not per-process, but system-wide */
+/* To be valid must be created with pid=-1 and cpu being a valid CPU. */
+/* Also usually only root can create these unless */
+/* /proc/sys/kernel/perf_event_paranoid is less than 1. */
+/* Most custom PMU types (uncore/northbridge/RAPL) are covered here. */
+
+static void create_mostly_valid_global_event(struct perf_event_attr *attr,
+ int group_leader)
+{
+
+ attr->type = random_event_type();
+ attr->size = random_attr_size();
+ attr->config = random_event_config(&attr->type,
+ &attr->config1,
+ &attr->config2);
+
+ attr->read_format = random_read_format();
+
+ /* Bitfield parameters, mostly boolean */
+ attr->disabled = rand_bool();
+ attr->inherit = rand_bool();
+ if (group_leader) {
+ attr->pinned = rand_bool();
+ }
+
+ /* Not setting most other paramaters */
+ /* As they tend to be not valid in a global event */
+}
+
/* Creates a completely random event, unlikely to be valid */
static void create_random_event(struct perf_event_attr *attr)
{
@@ -1244,7 +1274,7 @@ void sanitise_perf_event_open(int childno)
shm->syscall[childno].a2 = pid;
/* set up attr structure */
- switch (rand() % 3) {
+ switch (rand() % 4) {
case 0:
create_mostly_valid_counting_event(attr,group_leader);
break;
@@ -1252,6 +1282,9 @@ void sanitise_perf_event_open(int childno)
create_mostly_valid_sampling_event(attr,group_leader);
break;
case 2:
+ create_mostly_valid_global_event(attr,group_leader);
+ break;
+ case 3:
create_random_event(attr);
break;
default:
--
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