diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index bf962051af0a076ce4bc0d68c1b04f8e915451ba..2e92e87ac0e34533a4c3b7c6bd64c22ea17cd502 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -21,6 +21,7 @@
 #include <linux/completion.h>
 #include <linux/cpumask.h>
 #include <linux/memblock.h>
+#include <linux/nospec.h>
 #include <linux/slab.h>
 #include <linux/reboot.h>
 #include <linux/syscalls.h>
@@ -1168,6 +1169,9 @@ 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)