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

On Wed, Oct 28, 2020 at 05:43:01PM +0000, Mike Leach wrote:

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

---

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;

Yes, obviously - thanks for catching that.

As checkpatch has complained about, the Fixes line you added isn't correct. It should have been:

Fixes: bb1860efc817 ("coresight: etm: perf: Sink selection using sysfs is deprecated")

I made the modification and applied to my tree.

Thanks, Mathieu

struct etm_event_data *event_data = NULL; event_data = alloc_event_data(cpu); -- 2.17.1