Re: SCTP ABI breakage?

On Tue, Dec 21, 2021 at 5:50 PM Stephen Hemminger
[off-list ref] wrote:

Looks like changes to SCTP events create kernel ABI breakage in applications.

If application is compiled with new header but attempts to run on older kernel, it doesn't work:

Reported here: https://osmocom.org/issues/5366

Looks like bad design assumptions about how setsockopt here:
static int sctp_setsockopt_events(struct sock *sk, __u8 *sn_type,
                                  unsigned int optlen)
{
        struct sctp_sock *sp = sctp_sk(sk);
        struct sctp_association *asoc;
        int i;

        if (optlen > sizeof(struct sctp_event_subscribe))
                return -EINVAL;

Because of that the commits that add new events cause code built with the new
header to not run on older kernels.

Hi, Stephen,

This is a known issue, and we're sorry that this can not be fixed.
please see:

https://lore.kernel.org/netdev/20200501131607.GU1294372@nataraja/ (local)

Thanks.