On Sat, 6 Feb 2021 12:36:48 -0800 Arjun Roy wrote:
> From: Arjun Roy <arjun...@google.com>
>
> Explicitly define reserved field and require it to be 0-valued.
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index e1a17c6b473c..c8469c579ed8 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -4159,6 +4159,8 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
> }
> if (copy_from_user(&zc, optval, len))
> return -EFAULT;
> + if (zc.reserved)
> + return -EINVAL;
> lock_sock(sk);
> err = tcp_zerocopy_receive(sk, &zc, &tss);
> release_sock(sk);
I was expecting we'd also throw in a check_zeroed_user().
Either we can check if the buffer is zeroed all the way,
or we can't and we shouldn't validate reserved either
check_zeroed_user(optval + offsetof(reserved),
len - offsetof(reserved))
?
