From: Yanmin Zhang <yanmin_zhang@linux.intel.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>,
kunx.jiang@intel.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ipv4: fix the rcu race between free_fib_info and ip_route_output_slow
Date: Wed, 23 May 2012 14:15:57 +0800 [thread overview]
Message-ID: <1337753757.14538.190.camel@ymzhang.sh.intel.com> (raw)
In-Reply-To: <1337749339.3361.1655.camel@edumazet-glaptop>
On Wed, 2012-05-23 at 07:02 +0200, Eric Dumazet wrote:
> On Wed, 2012-05-23 at 12:54 +0800, Yanmin Zhang wrote:
>
> > > fi->fib_dev (aka fib_nh[0].nh_dev) need full RCU protection.
> > The new patch posted at https://lkml.org/lkml/2012/5/22/558 does move the
> > resetting to RCU protection.
>
> Its not enough.
>
> We must take care that all users are in a RCU protected region.
>
> They might be already, but a full check is needed.
>
> For example
>
> net/ipv4/fib_trie.c:2563: fi->fib_dev ? fi->fib_dev->name : "*"
>
> looks to be safe (because already in a rcu_read_lock())
>
> But its not.
>
> Right thing would be to do :
>
> struct net_device *ndev = rcu_dereference(fi->fib_dev)
>
> ...
> ndev ? ndev->name : "*"
Thanks for the pointer.
Besides fi->fib_dev here, we need check fi->fib_hash, fi->fib_lhash,
and nexthop_nh->nh_hash.
Yanmin
next prev parent reply other threads:[~2012-05-23 6:15 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-22 9:48 [PATCH] ipv4: fix the rcu race between free_fib_info and ip_route_output_slow kun.jiang
2012-05-22 19:15 ` David Miller
2012-05-23 3:02 ` Yanmin Zhang
2012-05-23 3:23 ` David Miller
2012-05-23 3:30 ` Yanmin Zhang
2012-05-23 3:49 ` David Miller
2012-05-23 4:41 ` Yanmin Zhang
2012-05-23 5:08 ` Eric Dumazet
2012-05-23 4:37 ` Eric Dumazet
2012-05-23 4:54 ` Yanmin Zhang
2012-05-23 5:02 ` Eric Dumazet
2012-05-23 6:15 ` Yanmin Zhang [this message]
2012-05-23 6:27 ` Eric Dumazet
2012-05-23 6:47 ` Yanmin Zhang
2012-05-23 6:55 ` Eric Dumazet
2012-05-23 7:13 ` Eric Dumazet
2012-05-23 7:24 ` Yanmin Zhang
2012-05-23 7:39 ` Eric Dumazet
2012-05-23 7:41 ` Eric Dumazet
2012-05-23 7:47 ` Yanmin Zhang
2012-05-23 6:37 ` Eric Dumazet
2012-05-23 6:43 ` Eric Dumazet
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