Working on some new updates to trace filtering, I noticed that the

regex_match_front() test was updated to be limited to the size
 of the pattern instead of the full test string. But as the test string
 is not guaranteed to be nul terminated, it still needs to consider
 the size of the test string.
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Merge tag 'trace-v4.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fix from Steven Rostedt:
 "Working on some new updates to trace filtering, I noticed that the
  regex_match_front() test was updated to be limited to the size of the
  pattern instead of the full test string.

  But as the test string is not guaranteed to be nul terminated, it
  still needs to consider the size of the test string"

* tag 'trace-v4.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Fix regex_match_front() to not over compare the test string

kernel/trace/trace_events_filter.c

@@ -762,6 +762,9 @@ static int regex_match_full(char *str, struct regex *r, int len)
 
 static int regex_match_front(char *str, struct regex *r, int len)
 {
+	if (len < r->len)
+		return 0;
+
 	if (strncmp(str, r->pattern, r->len) == 0)
 		return 1;
 	return 0;