This is a note to let you know that I've just added the patch titled coresight: Fix uninitialised pointer bug in etm_setup_aux() to the 5.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: coresight-fix-uninitialised-pointer-bug-in-etm_setup_aux.patch and it can be found in the queue-5.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 39a7661dcf655c8198fd5d72412f5030a8e58444 Mon Sep 17 00:00:00 2001 From: Mike Leach <mike.leach@xxxxxxxxxx> Date: Thu, 29 Oct 2020 10:45:59 -0600 Subject: coresight: Fix uninitialised pointer bug in etm_setup_aux() From: Mike Leach <mike.leach@xxxxxxxxxx> commit 39a7661dcf655c8198fd5d72412f5030a8e58444 upstream. 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> Link: https://lore.kernel.org/r/20201029164559.1268531-3-mathieu.poirier@xxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/hwtracing/coresight/coresight-etm-perf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- 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_e 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); Patches currently in stable-queue which might be from mike.leach@xxxxxxxxxx are queue-5.9/coresight-fix-uninitialised-pointer-bug-in-etm_setup_aux.patch