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SubjectRe: [PATCH net] ipv6: sctp: clone options to avoid use after free
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On 12/09/2015 10:25 AM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> SCTP is lacking proper np->opt cloning at accept() time.
>
> TCP and DCCP use ipv6_dup_options() helper, do the same
> in SCTP.
>
> We might later factorize this code in a common helper to avoid
> future mistakes.
>
> Reported-by: Dmitry Vyukov <dvyukov@google.com>
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Acked-by: Vlad Yasevich <vyasevich@gmail.com>

This is sufficient for accept() processing, but looks like peeloff is missing
a bunch of ipv6 support. I'll see if I can cook something up to fix that part.

-vlad

> ---
> net/sctp/ipv6.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
> index d28c0b4c9128..ec529121f38a 100644
> --- a/net/sctp/ipv6.c
> +++ b/net/sctp/ipv6.c
> @@ -641,6 +641,7 @@ static struct sock *sctp_v6_create_accept_sk(struct sock *sk,
> struct sock *newsk;
> struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
> struct sctp6_sock *newsctp6sk;
> + struct ipv6_txoptions *opt;
>
> newsk = sk_alloc(sock_net(sk), PF_INET6, GFP_KERNEL, sk->sk_prot, 0);
> if (!newsk)
> @@ -660,6 +661,13 @@ static struct sock *sctp_v6_create_accept_sk(struct sock *sk,
>
> memcpy(newnp, np, sizeof(struct ipv6_pinfo));
>
> + rcu_read_lock();
> + opt = rcu_dereference(np->opt);
> + if (opt)
> + opt = ipv6_dup_options(newsk, opt);
> + RCU_INIT_POINTER(newnp->opt, opt);
> + rcu_read_unlock();
> +
> /* Initialize sk's sport, dport, rcv_saddr and daddr for getsockname()
> * and getpeername().
> */
>
>



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