tracing: Avoid string overflow

'err' is used as a NUL-terminated string, but using strncpy() with the length
equal to the buffer size may result in lack of the termination:

kernel/trace/trace_events_hist.c: In function 'hist_err_event':
kernel/trace/trace_events_hist.c:396:3: error: 'strncpy' specified bound 256 equals destination size [-Werror=stringop-truncation]
   strncpy(err, var, MAX_FILTER_STR_VAL);

This changes it to use the safer strscpy() instead.

Link: http://lkml.kernel.org/r/20180328140920.2842153-1-arnd@arndb.de

Cc: stable@vger.kernel.org
Fixes: f404da6e1d46 ("tracing: Add 'last error' error facility for hist triggers")
Acked-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 046c716a6536..aae18af94c94 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -393,7 +393,7 @@ static void hist_err_event(char *str, char *system, char *event, char *var)
         else if (system)
                 snprintf(err, MAX_FILTER_STR_VAL, "%s.%s", system, event);
         else
-                strncpy(err, var, MAX_FILTER_STR_VAL);
+                strscpy(err, var, MAX_FILTER_STR_VAL);
 
         hist_err(str, err);
 }