Re: [PATCH 7/9 linux-next] fanotify: don't write with zero size

[Amir Goldstein <amir73il@xxxxxxxxx>]

On Mon, May 11, 2020 at 9:02 PM Fabian Frederick <fabf@xxxxxxxxx> wrote:
>
> check count in fanotify_write() and return -EINVAL when 0
>
> Signed-off-by: Fabian Frederick <fabf@xxxxxxxxx>
> ---
>  fs/notify/fanotify/fanotify_user.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 02a314acc757..6e19dacb2475 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -485,6 +485,9 @@ static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t
>         if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS))
>                 return -EINVAL;
>
> +       if (!count)
> +               return -EINVAL;
> +

Maybe even (count < sizeof(response)) ?

>         group = file->private_data;
>
>         if (count > sizeof(response))
> --
> 2.26.2
>