Subject: Re: [PATCH net] net: sctp: fix copying sk_v6_rcv_saddr in sctp_v6_create_accept_sk

From: Vlad Yasevich <[email-masked]>
Date: Tue, 19 Nov 2013 10:38:10 -0500

On 11/19/2013 05:51 AM, Daniel Borkmann wrote:
> Wang reported an issue that lksctp's test_getname_v6 seems to fail.
> 
> The issue is that we do not copy sk_v6_rcv_saddr over to the new
> socket, although the comment above says so regarding rcv_saddr.
> 
> Commit 914e1c8b6980 ("sctp: Inherit all socket options from parent
> correctly.") originally moved that over to sctp_copy_sock(), but
> after commit efe4208f47f9 ("ipv6: make lookups simpler and faster")
> this no longer holds and the actual value of sk_v6_rcv_saddr was
> no longer being migrated.
> 
> With this patch, the lksctp test suite passes again for IPv6.
> 
> Fixes: efe4208f47f9 ("ipv6: make lookups simpler and faster")
> Signed-off-by: Daniel Borkmann <[email-masked]>
> Signed-off-by: Wang Weidong <[email-masked]>
> Cc: Eric Dumazet <[email-masked]>
> ---
>  net/sctp/ipv6.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> index 7567e6f..be08592 100644
> --- a/net/sctp/ipv6.c
> +++ b/net/sctp/ipv6.c
> @@ -661,6 +661,7 @@ static struct sock *sctp_v6_create_accept_sk(struct sock *sk,
>  	 * and getpeername().
>  	 */
>  	sctp_v6_to_sk_daddr(&asoc->peer.primary_addr, newsk);
> +	newsk->sk_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
>  
>  	sk_refcnt_debug_inc(newsk);
>  
> 

This fixes the issue for the accept() case, but the bug is still there
in the peeloff case.

I think you should make sctp_copy_sock() use sock_copy() for now.  It
looks like it will catch all the cases.

We can then look at possibly getting rid of sctp_copy_sock() for net-next.

-vlad