torture: Avoid format string leak to thead name

Since the torture-test thread creation interface does not include
format string arguments, this commit makes sure the name can never be
accidentally processed as a format string.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/kernel/torture.c b/kernel/torture.c
index 40bb511..d600af21 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -708,7 +708,7 @@
 	int ret = 0;
 
 	VERBOSE_TOROUT_STRING(m);
-	*tp = kthread_run(fn, arg, s);
+	*tp = kthread_run(fn, arg, "%s", s);
 	if (IS_ERR(*tp)) {
 		ret = PTR_ERR(*tp);
 		VERBOSE_TOROUT_ERRSTRING(f);