netdev - Re: [patch] RxRPC: use copy_to_user() instead of memcpy()

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Date:	Tue, 19 Mar 2013 13:59:30 +0000
From:	David Howells <dhowells@...hat.com>
To:	David Miller <davem@...emloft.net>, dan.carpenter@...cle.com
Cc:	dhowells@...hat.com, netdev@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [patch] RxRPC: use copy_to_user() instead of memcpy()

David Miller <davem@...emloft.net> wrote:

> >  		/* copy the peer address and timestamp */
> >  		if (!continue_call) {
> > -			if (msg->msg_name && msg->msg_namelen > 0)
> > -				memcpy(msg->msg_name,
> > -				       &call->conn->trans->peer->srx,
> > -				       sizeof(call->conn->trans->peer->srx));
> 
> I bet the size is too large for a sockaddr_storage, and therefore we
> spam the kernel stack.  So I can only guess that changing this to a
> copy_to_user() fixes the hang because it simply faults on the kernel
> destination address.

Maybe, though I don't see how that would just fix the hang rather than
oopsing.  If Dan can printk the following:

	msg->msg_namelen
	sizeof(call->conn->trans->peer->srx)

before doing the memcpy, that could be handy.

David
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