Re: kern/51467: detaching USB network interface panics

[Ryota Ozaki <ozaki-r%netbsd.org@localhost>]

On Mon, Sep 12, 2016 at 12:15 AM,  <mlelstv%serpens.de@localhost> wrote:
>>Number:         51467
>>Category:       kern
>>Synopsis:       detaching USB network interface panics
>>Confidential:   no
>>Severity:       critical
>>Priority:       medium
>>Responsible:    kern-bug-people
>>State:          open
>>Class:          sw-bug
>>Submitter-Id:   net
>>Arrival-Date:   Sun Sep 11 15:15:00 +0000 2016
>>Originator:     Michael van Elst
>>Release:        NetBSD 7.99.36
>>Organization:
>
>>Environment:
>
>
> System: NetBSD tazz 7.99.36 NetBSD 7.99.36 (TAZZ) #7: Sun Sep 11 16:12:19 CEST 2016 mlelstv@gossam:/home/netbsd-current/obj.amd64/home/netbsd-current/src/sys/arch/amd64/compile/TAZZ amd64
> Architecture: x86_64
> Machine: amd64
>>Description:
> Detaching a configured run(4) interface resulted in a panic.
>
> DDB shows:
>
> find_pfxlist_reachable_router.isra.6() at find_pfxlist_reachable_router.isra.6+0x11
> pfxlist_onlink_check() at pfxlist_onlink_check+0x132
> nd6_purge() at nd6_purge+0x103
> in6_ifdetach() at in6_ifdetach+0x1b
> udp6_purgeif_wrapper() at udp6_purgeif_wrapper+0x39
> if_detach() at if_detach+0x264
> run_detach() at run_detach+0x75
> config_detach() at config_detach+0xf8
> usb_disconnect_port() at usb_disconnect_port+0x18b
> uhub_explore() at uhub_explore+0x1fe
> uhub_explore() at uhub_explore+0xac
> usb_discover() at usb_discover+0x6f
> usb_event_thread() at usb_event_thread+0x238
>
> GDB shows more detail:
>
> #8  0xffffffff80566be7 in find_pfxlist_reachable_router (pr=<optimized out>)
>     at /home/netbsd-current/src/sys/netinet6/nd6_rtr.c:1416
> #9  0xffffffff80567a07 in pfxlist_onlink_check () at /home/netbsd-current/src/sys/netinet6/nd6_rtr.c:1576
> #10 0xffffffff8056800c in prelist_remove (pr=<optimized out>)
>     at /home/netbsd-current/src/sys/netinet6/nd6_rtr.c:1058
> #11 0xffffffff805610d6 in nd6_purge (ifp=ifp@entry=0xffff8000070f3008, ext=0xfffffe811e16aab8, ext@entry=0x0)
>     at /home/netbsd-current/src/sys/netinet6/nd6.c:866
> #12 0xffffffff8054cf7f in in6_ifdetach (ifp=ifp@entry=0xffff8000070f3008)
>     at /home/netbsd-current/src/sys/netinet6/in6_ifattach.c:815
>
>    0xffffffff80566bd6 <find_pfxlist_reachable_router>:  push   %rbp
>    0xffffffff80566bd7 <find_pfxlist_reachable_router+1>:        mov    %rsp,%rbp
>    0xffffffff80566bda <find_pfxlist_reachable_router+4>:        push   %rbx
>    0xffffffff80566bdb <find_pfxlist_reachable_router+5>:        sub    $0x8,%rsp
>    0xffffffff80566bdf <find_pfxlist_reachable_router+9>:        mov    %rdi,%rbx
>    0xffffffff80566be2 <find_pfxlist_reachable_router+12>:       test   %rdi,%rdi
>    0xffffffff80566be5 <find_pfxlist_reachable_router+15>:       je     0xffffffff80566c38 <find_pfxlist_reachable_router+98>
> => 0xffffffff80566be7 <find_pfxlist_reachable_router+17>:       mov    0x10(%rbx),%rdi
>    0xffffffff80566beb <find_pfxlist_reachable_router+21>:       mov    0x30(%rdi),%rsi
>    0xffffffff80566bef <find_pfxlist_reachable_router+25>:       testb  $0x1,0x4c(%rsi)
>
> rbx            0x2587e94bac0e70d2       2704386612477718738
>
> which is garbage.
>
>
>>How-To-Repeat:
> Detach a USB network interface that has IPv6 configured.

Do you know when it worked lastly?

If degraded by recent changes, one suspect is a change at 8/16(*).
Then could you try a kernel at 8/15?

(*) http://www.nerv.org/netbsd/?q=id:20160816T103157Z.479577018086b726daa7c1600fe5219e96a677d6

  ozaki-r