1 files changed, 3 insertions, 1 deletions

diff --git a/kernel/params.c b/kernel/params.c
index 795321aba29f..0af9b2c4e56c 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -645,7 +645,9 @@ static __modinit int add_sysfs_param(struct module_kobject *mk,
         sysfs_attr_init(&mk->mp->attrs[mk->mp->num].mattr.attr);
         mk->mp->attrs[mk->mp->num].param = kp;
         mk->mp->attrs[mk->mp->num].mattr.show = param_attr_show;
-        mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
+        /* Do not allow runtime DAC changes to make param writable. */
+        if ((kp->perm & (S_IWUSR | S_IWGRP | S_IWOTH)) != 0)
+                mk->mp->attrs[mk->mp->num].mattr.store = param_attr_store;
         mk->mp->attrs[mk->mp->num].mattr.attr.name = (char *)name;
         mk->mp->attrs[mk->mp->num].mattr.attr.mode = kp->perm;
         mk->mp->num++;