Re: [PATCH net] sctp: fix addip_serial increment on ASCONF_ACK allocation failure

On Tue, Jul 28, 2026 at 9:24=E2=80=AFPM Jakub Kicinski <[email protected]> wr=
ote:
>
> On Thu, 23 Jul 2026 15:18:18 +0800 luoqing wrote:
> > From: Qing Luo <[email protected]>
> >
> > In sctp_process_asconf(), when sctp_make_asconf_ack() fails to allocate
> > the ASCONF_ACK chunk due to memory pressure, the code jumps to the
> > done label where asoc->peer.addip_serial is unconditionally incremented=
.
> >
> > This leaves the peer's ASCONF (serial N) unacknowledged while the local
> > endpoint now expects serial N+1. When the peer retransmits serial N, it
> > falls into the serial < addip_serial + 1 branch ,
> > which attempts to look up a cached ACK for serial N. No cached ACK
> > exists since the allocation failed, so the retransmission is silently
> > discarded. The peer eventually times out and ABORTs the association.
> >
> > Move the addip_serial increment inside the if (asconf_ack) block so tha=
t
> > the serial number is only advanced when the ASCONF_ACK is successfully
> > created and cached. This way, on allocation failure, the serial number
> > is unchanged and the peer's retransmitted ASCONF will be correctly
> > re-processed.
> >
> > Fixes: 1da177e4c3f4 (Linux-2.6.12-rc2)
>
> nit: missing quotation marks around the subject
> --
> pw-bot: cr

Somehow I missed this patch.

LGTM, except the nit Jakub pointed out.

Thanks.