void lkdtm_USERCOPY_KERNEL_DS(void)
{
- char __user *user_ptr = (char __user *)ERR_PTR(-EINVAL);
+ char __user *user_ptr =
+ (char __user *)(0xFUL << (sizeof(unsigned long) * 8 - 4));
mm_segment_t old_fs = get_fs();
char buf[10] = {0};
- pr_info("attempting copy_to_user on unmapped kernel address\n");
+ pr_info("attempting copy_to_user() to noncanonical address: %px\n",
+ user_ptr);
set_fs(KERNEL_DS);
- if (copy_to_user(user_ptr, buf, sizeof(buf)))
- pr_info("copy_to_user un unmapped kernel address failed\n");
+ if (copy_to_user(user_ptr, buf, sizeof(buf)) == 0)
+ pr_err("copy_to_user() to noncanonical address succeeded!?\n");
set_fs(old_fs);
}