diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 7e0722b62cae90ab0674ca3dbfbd5ecb67389147..e39d25744ea2506911b71ec242e146a96d16dcd7 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -24,6 +24,7 @@
 #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>
@@ -1224,6 +1225,9 @@ 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)