[PATCH 2/2] coresight: Fix uninitialised pointer bug in etm_setup_aux()

From: Mathieu Poirier
Date: Thu Oct 29 2020 - 12:46:54 EST


From: Mike Leach <mike.leach@xxxxxxxxxx>

Commit [bb1860efc817] changed the sink handling code introducing an
uninitialised pointer bug. This results in the default sink selection
failing.

Prior to commit:

static void etm_setup_aux(...)

<snip>
struct coresight_device *sink;
<snip>

/* First get the selected sink from user space. */
if (event->attr.config2) {
id = (u32)event->attr.config2;
sink = coresight_get_sink_by_id(id);
} else {
sink = coresight_get_enabled_sink(true);
}
<ctd>

*sink always initialised - possibly to NULL which triggers the
automatic sink selection.

After commit:

static void etm_setup_aux(...)

<snip>
struct coresight_device *sink;
<snip>

/* First get the selected sink from user space. */
if (event->attr.config2) {
id = (u32)event->attr.config2;
sink = coresight_get_sink_by_id(id);
}
<ctd>

*sink pointer uninitialised when not providing a sink on the perf command
line. This breaks later checks to enable automatic sink selection.

Fixes: bb1860efc817 ("coresight: etm: perf: Sink selection using sysfs is deprecated")
Signed-off-by: Mike Leach <mike.leach@xxxxxxxxxx>
Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
---
drivers/hwtracing/coresight/coresight-etm-perf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
index c2c9b127d074..bdc34ca449f7 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -210,7 +210,7 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,
u32 id;
int cpu = event->cpu;
cpumask_t *mask;
- struct coresight_device *sink;
+ struct coresight_device *sink = NULL;
struct etm_event_data *event_data = NULL;

event_data = alloc_event_data(cpu);
--
2.25.1