Re: [PATCH net] net: sctp: fix bug in sctp_poll for SOCK_SELECT_ERR_QUEUE

[Vlad Yasevich <vyasevich@gmail.com>]

On 09/07/2013 10:44 AM, Daniel Borkmann wrote:
> If we do not add braces around ...
>
>    mask |= POLLERR |
>            sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? POLLPRI : 0;
>
> ... then this condition always evaluates to true as POLLERR is
> defined as 8 and binary or'd with whatever result comes out of
> sock_flag(). Hence instead of (X | Y) ? A : B, transform it into
> X | (Y ? A : B). Unfortunatelty, commit 8facd5fb73 ("net: fix
> smatch warnings inside datagram_poll") forgot about SCTP. :-(
>
> Introduced by 7d4c04fc170 ("net: add option to enable error queue
> packets waking select").
>
> Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
> Cc Jacob Keller <jacob.e.keller@intel.com>

Acked-by: Vlad Yasevich <vyasevich@gmail.com>

-vlad

> ---
>   net/sctp/socket.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index d5d5882..5462bbb 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -6176,7 +6176,7 @@ unsigned int sctp_poll(struct file *file, struct socket *sock, poll_table *wait)
>   	/* Is there any exceptional events?  */
>   	if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
>   		mask |= POLLERR |
> -			sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? POLLPRI : 0;
> +			(sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? POLLPRI : 0);
>   	if (sk->sk_shutdown & RCV_SHUTDOWN)
>   		mask |= POLLRDHUP | POLLIN | POLLRDNORM;
>   	if (sk->sk_shutdown == SHUTDOWN_MASK)
>