On Sat, Jun 17, 2017 at 04:10:27PM +0800, Xin Long wrote:
> Now before dumping a sock in sctp_diag, it only holds the sock while
> the ep may be already destroyed. It can cause a use-after-free panic
> when accessing ep->asocs.
> 
> This patch is to set sctp_sk(sk)->ep NULL in sctp_endpoint_destroy,
> and check if this ep is already destroyed before dumping this ep.
> 
> Suggested-by: Marcelo Ricardo Leitner <marcelo.leit...@gmail.com>
> Signed-off-by: Xin Long <lucien....@gmail.com>
> ---
>  net/sctp/endpointola.c | 1 +
>  net/sctp/sctp_diag.c   | 5 +++--
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/net/sctp/endpointola.c b/net/sctp/endpointola.c
> index 8c58923..3dcd0ec 100644
> --- a/net/sctp/endpointola.c
> +++ b/net/sctp/endpointola.c
> @@ -275,6 +275,7 @@ static void sctp_endpoint_destroy(struct sctp_endpoint 
> *ep)
>               if (sctp_sk(sk)->bind_hash)
>                       sctp_put_port(sk);
>  
> +             sctp_sk(sk)->ep = NULL;
>               sock_put(sk);
>       }
>  
> diff --git a/net/sctp/sctp_diag.c b/net/sctp/sctp_diag.c
> index 048954e..9a64721 100644
> --- a/net/sctp/sctp_diag.c
> +++ b/net/sctp/sctp_diag.c
> @@ -278,7 +278,6 @@ static int sctp_tsp_dump_one(struct sctp_transport *tsp, 
> void *p)
>  
>  static int sctp_sock_dump(struct sock *sk, void *p)
>  {
> -     struct sctp_endpoint *ep = sctp_sk(sk)->ep;
>       struct sctp_comm_param *commp = p;
>       struct sk_buff *skb = commp->skb;
>       struct netlink_callback *cb = commp->cb;
> @@ -287,7 +286,9 @@ static int sctp_sock_dump(struct sock *sk, void *p)
>       int err = 0;
>  
>       lock_sock(sk);
> -     list_for_each_entry(assoc, &ep->asocs, asocs) {
> +     if (!sctp_sk(sk)->ep)
> +             goto release;
> +     list_for_each_entry(assoc, &sctp_sk(sk)->ep->asocs, asocs) {
>               if (cb->args[4] < cb->args[1])
>                       goto next;
>  
> -- 
> 2.1.0
> 
> 
Acked-by: Neil Horman <nhor...@tuxdrver.com>

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