Re: [PATCH] net: Check the argument for listen(2)

[Eric Dumazet <eric.dumazet@gmail.com>]

On Sat, 2013-06-29 at 00:14 +0800, Changli Gao wrote:
> As we use u16 to save the value of the argument for listen(2),
> we'd better check if the value is larger than SINT_MAX other
> than cut it down silently on error.
> ---
>  net/ipv4/af_inet.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index b4d0be2..35aaf00 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -198,6 +198,9 @@ int inet_listen(struct socket *sock, int backlog)
>  	unsigned char old_state;
>  	int err;
>  
> +	if (backlog >= (1 << 16))
> +		return EINVAL;
> +
>  	lock_sock(sk);
>  
>  	err = -EINVAL;

This seems pretty buggy to me.

1) EINVAL is not -EINVAL

2) This might break existing applications.