linux-kernel - Re: [PATCH v2 1/3] pppoatm: don't send frames to destroyed vcc

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Message-ID: <20121030201937.GA9583@shrek.podlesie.net>
Date:	Tue, 30 Oct 2012 21:19:37 +0100
From:	Krzysztof Mazur <krzysiek@...lesie.net>
To:	David Woodhouse <dwmw2@...radead.org>
Cc:	davem@...emloft.net, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] pppoatm: don't send frames to destroyed vcc

On Tue, Oct 30, 2012 at 09:35:00AM +0000, David Woodhouse wrote:
> On Mon, 2012-10-22 at 19:14 +0200, Krzysztof Mazur wrote:
> > Now pppoatm_send(), like vcc_sendmsg(), checks for vcc flags that
> > indicate that vcc is not ready.
> 
> I note that vcc_sendmsg() also checks for sock->state == SS_CONNECTED.
> Is that check not needed here? Otherwise, looks sane enough.
> 
> Acked-By: David Woodhouse <David.Woodhouse@...el.com>

I don't think so. We never leave SS_CONNECTED state. This check is
done in vcc_sendmsg() because it's called from userspace.

However maybe we should check socket state before assigning vcc to
pppoatm (untested):

diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c
index 0dcb5dc..df06d14 100644
--- a/net/atm/pppoatm.c
+++ b/net/atm/pppoatm.c
@@ -414,6 +414,8 @@ static int pppoatm_ioctl(struct socket *sock, unsigned int cmd,
 			return -ENOIOCTLCMD;
 		if (!capable(CAP_NET_ADMIN))
 			return -EPERM;
+		if (sock->state != SS_CONNECTED)
+			return -EINVAL;
 		return pppoatm_assign_vcc(atmvcc, argp);
 		}
 	case PPPIOCGCHAN:

Thanks.

Krzysiek
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