[PATCH 4.14 129/159] tracing: Exclude generic fields from histograms

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>


[ Upstream commit a15f7fc20389a8827d5859907568b201234d4b79 ]

There are a small number of 'generic fields' (comm/COMM/cpu/CPU) that
are found by trace_find_event_field() but are only meant for
filtering.  Specifically, they unlike normal fields, they have a size
of 0 and thus wreak havoc when used as a histogram key.

Exclude these (return -EINVAL) when used as histogram keys.

Link: http://lkml.kernel.org/r/956154cbc3e8a4f0633d619b886c97f0f0edf7b4.1506105045.git.tom.zanussi@xxxxxxxxxxxxxxx

Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 kernel/trace/trace_events_hist.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -450,7 +450,7 @@ static int create_val_field(struct hist_
 	}
 
 	field = trace_find_event_field(file->event_call, field_name);
-	if (!field) {
+	if (!field || !field->size) {
 		ret = -EINVAL;
 		goto out;
 	}
@@ -548,7 +548,7 @@ static int create_key_field(struct hist_
 		}
 
 		field = trace_find_event_field(file->event_call, field_name);
-		if (!field) {
+		if (!field || !field->size) {
 			ret = -EINVAL;
 			goto out;
 		}