From: Mike Leach <mike.leach@linaro.org>
Date: Wed, 28 Oct 2020 17:43:01 +0000 (+0000)
Subject: coresight: Fix uninitialised pointer bug in etm_setup_aux()
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=1e5504656e5a78d096fe59a880fe2a9eb75f50e3;p=users%2Fhch%2Fblock.git

coresight: Fix uninitialised pointer bug in etm_setup_aux()

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@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---

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);