On Thu, Aug 31 2023, Vitaliy Makkoveev <m...@openbsd.org> wrote:
> On Thu, Aug 31, 2023 at 01:42:45PM +0200, Alexander Bluhm wrote:
>> On Thu, Aug 31, 2023 at 01:05:11PM +0300, Vitaliy Makkoveev wrote:
>> > On Thu, Aug 31, 2023 at 11:26:42AM +0200, Jeremie Courreges-Anglas wrote:
>> > >
>> > > Looks umb(4) triggers the NET_ASSERT_LOCKED() check in
>> > > rtable_getsource() when the umb(4) interface comes up (here with
>> > > kern.splassert=2 to get context). Reproduced with GENERIC.MP from Aug
>> > > 28 as well with cvs HEAD/if_umb.c rev 1.54.
>> > >
>> > > Something to worry about?
>> > >
>> > >
>> > > OpenBSD 7.3-current (GENERIC.MP) #1357: Mon Aug 28 20:14:09 MDT 2023
>> > > dera...@amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP
>> > > [...]
>> > > umb0 at uhub0 port 3 configuration 1 interface 0 "FIBOCOM L831-EAU-00"
>> > > rev 2.00/17.29 addr 2
>> > > [...]
>> > > splassert: rtable_getsource: want 2 have 0
>> > > Starting stack trace...
>> > > rtable_getsource(0,2) at rtable_getsource+0x58
>> > > rtm_send(fffffd83b1a817e0,1,0,0) at rtm_send+0xbc
>> > > umb_add_inet_config(ffff8000017c7000,edf0e72e,18,1f0e72e) at
>> > > umb_add_inet_config+0x2a8
>> > > umb_decode_ip_configuration(ffff8000017c7000,ffff800001ccf230,50) at
>> > > umb_decode_ip_configuration+0x147
>> > > umb_get_response_task(ffff8000017c7000) at umb_get_response_task+0xda
>> > > usb_task_thread(ffff800022fe0010) at usb_task_thread+0xe5
>> > > end trace frame: 0x0, count: 251
>> > > End of stack trace.
>> > >
>> >
>> > rtable_getsource() requires at least shared netlock to be held. It can't
>> > be taken within rtm_send() because we have paths where caller already
>> > holds it.
>>
>> I am not sure if rtm_miss() a few lines above should run without
>> netlock. Could we just move the NET_UNLOCK() currenly above the
>> if block after the else block?
>>
>
> I could miss something, but I don't see rtm_miss() and rtm_msg1() touch
> rti_ifa which is netlock protected. The rest of info data is local to
> umb_add_inet{,6}_config() or immutable, so nothing requires netlock
> here. route_input() is just mbuf allocation and transmission to the
> route sockets.
>
>> NET_UNLOCK() and NET_LOCK_SHARED() just after each other does not
>> make much sense. Just keep exclusive netlock for the few lines.
>>
>
> Agreed. Both the cases perform route sockets walkthrough and message
> transmission. No sense for lockless error path only.
Works for me, ok jca@
> Index: sys/dev/usb/if_umb.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/usb/if_umb.c,v
> retrieving revision 1.54
> diff -u -p -r1.54 if_umb.c
> --- sys/dev/usb/if_umb.c 29 Aug 2023 23:28:38 -0000 1.54
> +++ sys/dev/usb/if_umb.c 31 Aug 2023 13:20:21 -0000
> @@ -1851,7 +1851,6 @@ umb_add_inet_config(struct umb_softc *sc
> info.rti_info[RTAX_GATEWAY] = sintosa(&ifra.ifra_dstaddr);
>
> rv = rtrequest(RTM_ADD, &info, 0, &rt, ifp->if_rdomain);
> - NET_UNLOCK();
> if (rv) {
> printf("%s: unable to set IPv4 default route, "
> "error %d\n", DEVNAM(ifp->if_softc), rv);
> @@ -1862,6 +1861,7 @@ umb_add_inet_config(struct umb_softc *sc
> rtm_send(rt, RTM_ADD, rv, ifp->if_rdomain);
> rtfree(rt);
> }
> + NET_UNLOCK();
>
> if (ifp->if_flags & IFF_DEBUG) {
> char str[3][INET_ADDRSTRLEN];
> @@ -1932,7 +1932,6 @@ umb_add_inet6_config(struct umb_softc *s
> info.rti_info[RTAX_GATEWAY] = sin6tosa(&ifra.ifra_dstaddr);
>
> rv = rtrequest(RTM_ADD, &info, 0, &rt, ifp->if_rdomain);
> - NET_UNLOCK();
> if (rv) {
> printf("%s: unable to set IPv6 default route, "
> "error %d\n", DEVNAM(ifp->if_softc), rv);
> @@ -1943,6 +1942,7 @@ umb_add_inet6_config(struct umb_softc *s
> rtm_send(rt, RTM_ADD, rv, ifp->if_rdomain);
> rtfree(rt);
> }
> + NET_UNLOCK();
>
> if (ifp->if_flags & IFF_DEBUG) {
> char str[3][INET6_ADDRSTRLEN];
>
--
jca | PGP : 0x1524E7EE / 5135 92C1 AD36 5293 2BDF DDCC 0DFA 74AE 1524 E7EE
