RE: [PATCH net-next 5/5] sctp: add spt_pathcpthld in struct sctp_paddrthlds

[David Laight <David.Laight@ACULAB.COM>]

From: Xin Long
> Sent: 09 September 2019 08:57
> Section 7.2 of rfc7829: "Peer Address Thresholds (SCTP_PEER_ADDR_THLDS)
> Socket Option" extends 'struct sctp_paddrthlds' with 'spt_pathcpthld'
> added to allow a user to change ps_retrans per sock/asoc/transport, as
> other 2 paddrthlds: pf_retrans, pathmaxrxt.
> 
> Note that ps_retrans is not allowed to be greater than pf_retrans.
> 
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
> ---
>  include/uapi/linux/sctp.h |  1 +
>  net/sctp/socket.c         | 10 ++++++++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
> index a15cc28..dfd81e1 100644
> --- a/include/uapi/linux/sctp.h
> +++ b/include/uapi/linux/sctp.h
> @@ -1069,6 +1069,7 @@ struct sctp_paddrthlds {
>  	struct sockaddr_storage spt_address;
>  	__u16 spt_pathmaxrxt;
>  	__u16 spt_pathpfthld;
> +	__u16 spt_pathcpthld;
>  };
> 
>  /*
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 5e2098b..5b9774d 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -3954,6 +3954,9 @@ static int sctp_setsockopt_paddr_thresholds(struct sock *sk,

This code does:
	if (optlen < sizeof(struct sctp_paddrthlds))
		return -EINVAL;

So adding an extra field breaks existing application binaries
that use this option.

I've not checked the other patches or similar fubar.

	David

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