diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index f8d3caad4cf3..3c06c8389e05 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -25,6 +25,7 @@
 #include <linux/reboot.h>
 #include <linux/security.h>
 #include <linux/syscalls.h>
+#include <linux/nospec.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
 
@@ -1178,6 +1179,9 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
 	    || nargs + nret > ARRAY_SIZE(args.args))
 		return -EINVAL;
 
+	nargs = array_index_nospec(nargs, ARRAY_SIZE(args.args));
+	nret = array_index_nospec(nret, ARRAY_SIZE(args.args) - nargs);
+
 	/* Copy in args. */
 	if (copy_from_user(args.args, uargs->args,
 			   nargs * sizeof(rtas_arg_t)) != 0)