tracing: Check keys for variable references in expressions too

There's an existing check for variable references in keys, but it
doesn't go far enough.  It checks whether a key field is a variable
reference but doesn't check whether it's an expression containing
variable references, which can cause the same problems for callers.

Use the existing field_has_hist_vars() function rather than a direct
top-level flag check to catch all possible variable references.

Link: http://lkml.kernel.org/r/e8c3d3d53db5ca90ceea5a46e5413103a6902fc7.1555597045.git.tom.zanussi@linux.intel.com
Cc: stable@vger.kernel.org
Fixes: 067fe038e70f6 ("tracing: Add variable reference handling to hist triggers")
Reported-by: Vincent Bernat <vincent@bernat.ch>
Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 06e7b9f66de6d40c508032e77eef0e7e5386ebc5..2b76f9520bd0a8c633da34db5c206b7294bfbcc4 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -59,7 +59,7 @@
        C(NO_CLOSING_PAREN,     "No closing paren found"),              \
        C(SUBSYS_NOT_FOUND,     "Missing subsystem"),                   \
        C(INVALID_SUBSYS_EVENT, "Invalid subsystem or event name"),     \
-       C(INVALID_REF_KEY,      "Using variable references as keys not supported"), \
+       C(INVALID_REF_KEY,      "Using variable references in keys not supported"), \
        C(VAR_NOT_FOUND,        "Couldn't find variable"),              \
        C(FIELD_NOT_FOUND,      "Couldn't find field"),
 
@@ -4506,7 +4506,7 @@ static int create_key_field(struct hist_trigger_data *hist_data,
                        goto out;
                }
 
-               if (hist_field->flags & HIST_FIELD_FL_VAR_REF) {
+               if (field_has_hist_vars(hist_field, 0)) {
                        hist_err(tr, HIST_ERR_INVALID_REF_KEY, errpos(field_str));
                        destroy_hist_field(hist_field, 0);
                        ret = -EINVAL;