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From: David Ahern <dsahern@gmail.com>
To: Marek Majkowski <marek@cloudflare.com>,
	David Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org, kernel-team <kernel-team@cloudflare.com>
Subject: Re: NEIGH: BUG, double timer add, state is 8
Date: Fri, 5 Jul 2019 08:28:15 -0600	[thread overview]
Message-ID: <1f4be489-4369-01d1-41c6-1406006df9c5@gmail.com> (raw)
In-Reply-To: <CAJPywTJWQ9ACrp0naDn0gikU4P5-xGcGrZ6ZOKUeeC3S-k9+MA@mail.gmail.com>

On 7/4/19 3:59 PM, Marek Majkowski wrote:
> I found a way to hit an obscure BUG in the
> net/core/neighbour.c:neigh_add_timer(), by piping two carefully
> crafted messages into AF_NETLINK socket.
> 
> https://github.com/torvalds/linux/blob/v5.2-rc7/net/core/neighbour.c#L259
> 
>     if (unlikely(mod_timer(&n->timer, when))) {
>         printk("NEIGH: BUG, double timer add, state is %x\n", n->nud_state);
>         dump_stack();
>      }
> 
> The repro is here:
> https://gist.github.com/majek/d70297b9d72bc2e2b82145e122722a0c
> 
> wget https://gist.githubusercontent.com/majek/d70297b9d72bc2e2b82145e122722a0c/raw/9e140bcedecc28d722022f1da142a379a9b7a7b0/double_timer_add_bug.c

Thanks for the report - and the reproducer. I am on PTO through Monday;
I will take a look next week if no one else does.

  reply	other threads:[~2019-07-05 14:28 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-04 21:59 NEIGH: BUG, double timer add, state is 8 Marek Majkowski
2019-07-05 14:28 ` David Ahern [this message]
2019-07-05 17:30   ` Lorenzo Bianconi
2019-07-10 22:18     ` David Ahern
2019-07-11  7:54       ` Lorenzo Bianconi

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