netdev - Re: [PATCH net] net: sctp: fix bug in sctp_poll for SOCK_SELECT_ERR

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Date:	Mon, 9 Sep 2013 19:12:03 +0000
From:	"Keller, Jacob E" <jacob.e.keller@...el.com>
To:	Vlad Yasevich <vyasevich@...il.com>
CC:	Daniel Borkmann <dborkman@...hat.com>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-sctp@...r.kernel.org" <linux-sctp@...r.kernel.org>
Subject: Re: [PATCH net] net: sctp: fix bug in sctp_poll for
 SOCK_SELECT_ERR_QUEUE

On Mon, 2013-09-09 at 09:56 -0400, Vlad Yasevich wrote:
> 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@...hat.com>
> > Cc Jacob Keller <jacob.e.keller@...el.com>
> 
> Acked-by: Vlad Yasevich <vyasevich@...il.com>

Acked-by: Jacob Keller <jacob.e.keller@...el.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)
> >
>