netdev - Re: ipv6: handle -EFAULT from skb_copy

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Message-ID: <20161220003144.omoqyghgdfbxdyuu@codemonkey.org.uk>
Date:   Mon, 19 Dec 2016 19:31:44 -0500
From:   Dave Jones <davej@...emonkey.org.uk>
To:     David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: Re: ipv6: handle -EFAULT from skb_copy_bits

On Mon, Dec 19, 2016 at 02:48:48PM -0500, David Miller wrote:

 > One thing that's interesting is that if the user picks "IPPROTO_RAW"
 > as the value of 'protocol' we set inet->hdrincl to 1.
 > 
 > The user can also set inet->hdrincl to 1 or 0 via setsockopt().
 > 
 > I think this is part of the problem.  The test above means to check
 > for "RAW socket with hdrincl set" and is trying to do this more simply.
 > But because setsockopt() can set this arbitrarily, testing sk_protocol
 > alone isn't enough.
 > 
 > So changing:
 > 
 > 	sk->sk_protocol == IPPROTO_RAW
 > 
 > into something like:
 > 
 > 	(sk->sk_socket->type == SOCK_RAW && inet_sk(sk)->hdrincl)
 > 
 > should correct the test.
 >  ..
 > 
 > You can test if the change I suggest above works.

Unfortunately, this made no difference.  I spent some time today trying
to make a better reproducer, but failed. I'll revisit again tomorrow.

Maybe I need >1 process/thread to trigger this.  That would explain why
I can trigger it with Trinity.

	Dave