[PATCH] tools lib traceevent: Fix buffer overflow in arg_eval

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

From: Tony Jones <tonyj@suse.de>

Fix buffer overflow observed when running perf test.

The overflow is when trying to evaluate "1ULL << (64 - 1)" which is
resulting in -9223372036854775808 which overflows the 20 character
buffer.

If is possible this bug has been reported before but I still don't see
any fix checked in:

See: https://www.spinics.net/lists/linux-perf-users/msg07714.html

Reported-by: Michael Sartain <mikesart@fastmail.com>
Reported-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Tony Jones <tonyj@suse.de>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Fixes: f7d82350e597 ("tools/events: Add files to create libtraceevent.a")
Link: http://lkml.kernel.org/r/20190228015532.8941-1-tonyj@suse.de
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
[
  Backport from kernel into the trace-cmd repo.
]

 lib/traceevent/event-parse.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/traceevent/event-parse.c b/lib/traceevent/event-parse.c
index 7cb2ae4..b36b536 100644
--- a/lib/traceevent/event-parse.c
+++ b/lib/traceevent/event-parse.c
@@ -2456,7 +2456,7 @@ static int arg_num_eval(struct tep_print_arg *arg, long long *val)
 static char *arg_eval (struct tep_print_arg *arg)
 {
 	long long val;
-	static char buf[20];
+	static char buf[24];
 
 	switch (arg->type) {
 	case TEP_PRINT_ATOM:
-- 
2.21.0