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Date:      Wed, 22 Jul 2020 06:54:17 +0200
From:      Peter Libassi <peter@libassi.se>
To:        John-Mark Gurney <jmg@funkthat.com>
Cc:        Marko Zec <zec@fer.hr>, freebsd-net@freebsd.org, freebsd-current@freebsd.org
Subject:   Re: somewhat reproducable vimage panic
Message-ID:  <38F5A3A6-B578-4BA4-8F69-C248163CB6E0@libassi.se>
In-Reply-To: <20200721202323.GE4213@funkthat.com>
References:  <20200721091654.GC4213@funkthat.com> <20200721113153.42d83119@x23> <20200721202323.GE4213@funkthat.com>

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Is this related to=20

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D234985 =
<https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D234985>; and =
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D238326 =
<https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D238326>;

/Peter


> 21 juli 2020 kl. 22:23 skrev John-Mark Gurney <jmg@funkthat.com>:
>=20
> Marko Zec wrote this message on Tue, Jul 21, 2020 at 11:31 +0200:
>> On Tue, 21 Jul 2020 02:16:55 -0700
>> John-Mark Gurney <jmg@funkthat.com> wrote:
>>=20
>>> I'm running:
>>> FreeBSD test 13.0-CURRENT FreeBSD 13.0-CURRENT #0 r362596: Thu Jun =
25
>>> 05:02:51 UTC 2020
>>> =
root@releng1.nyi.freebsd.org:/usr/obj/usr/src/amd64.amd64/sys/GENERIC
>>> amd64
>>>=20
>>> and I'm working on improve the if_ure driver.  I've put together a
>>> little script that I've attached that I'm using to test the driver..
>>> It puts a couple ue interfaces each into their own jail, configures
>>> them, and tries to pass traffic.  This assumes that the two =
interfaces
>>> are connected together.
>>>=20
>>> Pretty regularly when destroying the jails, I get the following
>>> panic: CURVNET_SET at /usr/src/sys/netinet/in_mcast.c:626
>>> inm_release() curvnet=3D0 vnet=3D0xfffff80154c82a80
>>=20
>> Perhaps the attached patch could help? (disclaimer: not even
>> compile-tested)
>=20
> The patch compiled, but it just moved the panic earlier than before.
>=20
> #4  0xffffffff80bc2123 in panic (fmt=3D<unavailable>)
>    at ../../../kern/kern_shutdown.c:839
> #5  0xffffffff80d61726 in inm_release_task (arg=3D<optimized out>,=20
>    pending=3D<optimized out>) at ../../../netinet/in_mcast.c:633
> #6  0xffffffff80c2166a in taskqueue_run_locked =
(queue=3D0xfffff800033cfd00)
>    at ../../../kern/subr_taskqueue.c:476
> #7  0xffffffff80c226e4 in taskqueue_thread_loop (arg=3D<optimized =
out>)
>    at ../../../kern/subr_taskqueue.c:793
>=20
> Now it panics at the location of the new CURVNET_SET and not the
> old one..
>=20
> Ok, decided to dump the contents of the vnet, and it looks like
> it's a use after free:
> (kgdb) print/x *(struct vnet *)0xfffff8012a283140
> $2 =3D {vnet_le =3D {le_next =3D 0xdeadc0dedeadc0de, le_prev =3D =
0xdeadc0dedeadc0de}, vnet_magic_n =3D 0xdeadc0de,=20
>  vnet_ifcnt =3D 0xdeadc0de, vnet_sockcnt =3D 0xdeadc0de, vnet_state =3D =
0xdeadc0de, vnet_data_mem =3D 0xdeadc0dedeadc0de,=20
>  vnet_data_base =3D 0xdeadc0dedeadc0de, vnet_shutdown =3D 0xde}
>=20
> The patch did seem to make it happen quicker, or maybe I was just more
> lucky this morning...
>=20
>>> (kgdb) #0  __curthread () at =
/usr/src/sys/amd64/include/pcpu_aux.h:55
>>> #1  doadump (textdump=3D1) at /usr/src/sys/kern/kern_shutdown.c:394
>>> #2  0xffffffff80bc6250 in kern_reboot (howto=3D260)
>>>    at /usr/src/sys/kern/kern_shutdown.c:481
>>> #3  0xffffffff80bc66aa in vpanic (fmt=3D<optimized out>, =
ap=3D<optimized
>>> out>) at /usr/src/sys/kern/kern_shutdown.c:913
>>> #4  0xffffffff80bc6403 in panic (fmt=3D<unavailable>)
>>>    at /usr/src/sys/kern/kern_shutdown.c:839
>>> #5  0xffffffff80d6553b in inm_release (inm=3D0xfffff80029043700)
>>>    at /usr/src/sys/netinet/in_mcast.c:630
>>> #6  inm_release_task (arg=3D<optimized out>, pending=3D<optimized =
out>)
>>>    at /usr/src/sys/netinet/in_mcast.c:312
>>> #7  0xffffffff80c2521a in taskqueue_run_locked
>>> (queue=3D0xfffff80003116b00) at =
/usr/src/sys/kern/subr_taskqueue.c:476
>>> #8  0xffffffff80c26294 in taskqueue_thread_loop (arg=3D<optimized =
out>)
>>>    at /usr/src/sys/kern/subr_taskqueue.c:793
>>> #9  0xffffffff80b830f0 in fork_exit (
>>>    callout=3D0xffffffff80c26200 <taskqueue_thread_loop>,=20
>>>    arg=3D0xffffffff81cf4f70 <taskqueue_thread>,
>>> frame=3D0xfffffe0049e99b80) at /usr/src/sys/kern/kern_fork.c:1052
>>> #10 <signal handler called>
>>> (kgdb)=20
>>>=20
>>> I have the core files so I can get additional information.
>>>=20
>>> Let me know if you need any additional information.
>>>=20
>>=20
>=20
>> Index: sys/netinet/in_mcast.c
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> --- sys/netinet/in_mcast.c	(revision 363386)
>> +++ sys/netinet/in_mcast.c	(working copy)
>> @@ -309,8 +309,10 @@
>> 	IN_MULTI_LOCK();
>> 	SLIST_FOREACH_SAFE(inm, &inm_free_tmp, inm_nrele, tinm) {
>> 		SLIST_REMOVE_HEAD(&inm_free_tmp, inm_nrele);
>> +		CURVNET_SET(inm->inm_ifp->if_vnet);
>> 		MPASS(inm);
>> 		inm_release(inm);
>> +		CURVNET_RESTORE();
>> 	}
>> 	IN_MULTI_UNLOCK();
>> }
>=20
>=20
> --=20
>  John-Mark Gurney				Voice: +1 415 225 5579
>=20
>     "All that I will do, has been done, All that I have, has not."
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