Re: git: b279e84a47dd - main - sctp: improve consistency

From: Kristof Provost <kp_at_FreeBSD.org>
Date: Fri, 04 Aug 2023 13:03:50 UTC 
On 29 Jul 2023, at 0:03, Michael Tuexen wrote:
> The branch main has been updated by tuexen:
>
> URL: 
> https://cgit.FreeBSD.org/src/commit/?id=b279e84a47ddb59e55b5a3cec31c51cd41bf0dc3
>
> commit b279e84a47ddb59e55b5a3cec31c51cd41bf0dc3
> Author:     Michael Tuexen <tuexen@FreeBSD.org>
> AuthorDate: 2023-07-28 12:36:11 +0000
> Commit:     Michael Tuexen <tuexen@FreeBSD.org>
> CommitDate: 2023-07-28 12:36:11 +0000
>
>     sctp: improve consistency
>
>     This is simplifying a patch to address PR 260116.
>
>     PR:             260116
>     MFC after:      1 week

It looks like this commit (or maybe the next one, 
c620788150d274c09a070ab486602c98407d73b0) causes a panic in the SCTP 
code during the `sys/netpfil/pf/sctp:basic_v4` test:

	panic: Counter goes negative
	cpuid = 7
	time = 1691145655
	KDB: stack backtrace:
	db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 
0xfffffe026ea9a3a0
	vpanic() at vpanic+0x132/frame 0xfffffe026ea9a4d0
	panic() at panic+0x43/frame 0xfffffe026ea9a530
	sctp_abort_notification() at sctp_abort_notification/frame 
0xfffffe026ea9a540
	sctp_express_handle_sack() at sctp_express_handle_sack+0x647/frame 
0xfffffe026ea9a640
	sctp_process_control() at sctp_process_control+0xf62/frame 
0xfffffe026ea9a990
	sctp_common_input_processing() at 
sctp_common_input_processing+0x561/frame 0xfffffe026ea9ab10
	sctp_input_with_port() at sctp_input_with_port+0x1fa/frame 
0xfffffe026ea9abe0
	sctp_input() at sctp_input+0x10/frame 0xfffffe026ea9abf0
	ip_input() at ip_input+0x2ab/frame 0xfffffe026ea9ac50
	netisr_dispatch_src() at netisr_dispatch_src+0xad/frame 
0xfffffe026ea9acb0
	ether_demux() at ether_demux+0x17a/frame 0xfffffe026ea9ace0
	ether_nh_input() at ether_nh_input+0x39f/frame 0xfffffe026ea9ad30
	netisr_dispatch_src() at netisr_dispatch_src+0xad/frame 
0xfffffe026ea9ad90
	ether_input() at ether_input+0xd9/frame 0xfffffe026ea9adf0
	epair_tx_start_deferred() at epair_tx_start_deferred+0xd7/frame 
0xfffffe026ea9ae40
	taskqueue_run_locked() at taskqueue_run_locked+0xab/frame 
0xfffffe026ea9aec0
	taskqueue_thread_loop() at taskqueue_thread_loop+0xd3/frame 
0xfffffe026ea9aef0
	fork_exit() at fork_exit+0x82/frame 0xfffffe026ea9af30
	fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe026ea9af30
	--- trap 0, rip = 0x35c39ec8bda0, rsp = 0, rbp = 0x35c39ec8ec90 ---
	KDB: enter: panic

That seems to be panicking during SCTP packet handling, so I do not 
believe this to be a pf bug.

Reverting both commits avoids the problem.

It’s also failing during the CI tests: 
https://ci.freebsd.org/view/Test/job/FreeBSD-main-amd64-test/23957/console

(To reproduce, kldload pf sctp ; cd /usr/tests/sys/netpfil/pf ; sudo 
kyua test sctp:basic_v4).

Best regards,
Kristof