diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 46b9476d75824937fae1352548587396096712a7..dc294c95da21cbf453d0914621feb2c736579dbd 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -18,6 +18,7 @@
 #include <linux/kernel.h>
 #include <linux/lockdep.h>
 #include <linux/memblock.h>
+#include <linux/nospec.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/reboot.h>
@@ -1839,6 +1840,9 @@ 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)