On Tue, Dec 15, 2020 at 06:23:18PM +0530, Siddhesh Poyarekar wrote:
> +static char *copy_mount_devname(const void __user *data)
> +{
> + char *p;
> + long length;
> +
> + if (data == NULL)
> + return NULL;
> +
> + length = strnlen_user(data, PATH_MAX);
> +
> + if (!length)
> + return ERR_PTR(-EFAULT);
> +
> + if (length > PATH_MAX)
> + return ERR_PTR(-EINVAL);
> +
> + /* Ignore blank strings */
> + if (length == 1)
> + return NULL;
> +
> + p = memdup_user(data, length);
Once more, with feeling: why bother? What's wrong
with using the damn strndup_user() and then doing
whatever checks you want with the data already
copied, living in normal kernel memory, with all
string functions applicable, etc.?
