From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>,
syzbot <syzbot+c2775460db0e1c70018e@syzkaller.appspotmail.com>,
netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com,
davem@davemloft.net, linux-kernel@vger.kernel.org,
pabeni@redhat.com, wireguard@lists.zx2c4.com, jann@thejh.net
Subject: Re: [syzbot] [wireguard?] KASAN: slab-use-after-free Write in enqueue_timer
Date: Tue, 23 May 2023 18:42:53 +0200 [thread overview]
Message-ID: <CAHmME9obRJPrjiJE95JZug0r6NUwrwwWib+=LO4jiQf-y2m+Vg@mail.gmail.com> (raw)
In-Reply-To: <20230523094108.0c624d47@kernel.org>
On Tue, May 23, 2023 at 6:41 PM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Tue, 23 May 2023 18:12:32 +0200 Eric Dumazet wrote:
> > > Your timer had the pleasure of getting queued _after_ a dead watchdog
> > > timer, no? IOW it tries to update the ->next pointer of a queued
> > > watchdog timer. We should probably do:
> > >
> > > diff --git a/net/core/dev.c b/net/core/dev.c
> > > index 374d38fb8b9d..f3ed20ebcf5a 100644
> > > --- a/net/core/dev.c
> > > +++ b/net/core/dev.c
> > > @@ -10389,6 +10389,8 @@ void netdev_run_todo(void)
> > > WARN_ON(rcu_access_pointer(dev->ip_ptr));
> > > WARN_ON(rcu_access_pointer(dev->ip6_ptr));
> > >
> > > + WARN_ON(timer_shutdown_sync(&dev->watchdog_timer));
> > > +
> > > if (dev->priv_destructor)
> > > dev->priv_destructor(dev);
> > > if (dev->needs_free_netdev)
> > >
> > > to catch how that watchdog_timer is getting queued. Would that make
> > > sense, Eric?
> >
> > Would this case be catched at the time the device is freed ?
> >
> > (CONFIG_DEBUG_OBJECTS_FREE=y or something)
>
> It should, no idea why it isn't. Looking thru the code now I don't see
> any obvious gaps where timer object is on a list but not active :S
> There's no way to get a vmcore from syzbot, right? :)
>
> Also I thought the shutdown leads to a warning when someone tries to
> schedule the dead timer but in fact add_timer() just exits cleanly.
> So the shutdown won't help us find the culprit :(
Worth noting that it could also be caused by adding to a dead timer
anywhere in priv_data of another netdev, not just the sole timer_list
in net_device.
next prev parent reply other threads:[~2023-05-23 16:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-30 18:01 syzbot
2023-05-23 15:46 ` Jason A. Donenfeld
2023-05-23 16:05 ` Jakub Kicinski
2023-05-23 16:12 ` Eric Dumazet
2023-05-23 16:41 ` Jakub Kicinski
2023-05-23 16:42 ` Jason A. Donenfeld [this message]
2023-05-23 16:47 ` Jakub Kicinski
2023-05-23 17:01 ` Jason A. Donenfeld
2023-05-23 17:05 ` Eric Dumazet
2023-05-23 17:07 ` Eric Dumazet
2023-05-24 8:24 ` Dmitry Vyukov
2023-05-24 15:33 ` Jakub Kicinski
2023-05-24 15:39 ` Jakub Kicinski
2023-05-23 16:14 ` Jason A. Donenfeld
2023-05-23 16:46 ` Jakub Kicinski
2023-05-23 16:47 ` Jason A. Donenfeld
2023-05-23 17:16 ` Jason A. Donenfeld
2023-05-23 17:28 ` Jason A. Donenfeld
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