From: David Miller <davem@davemloft.net>
To: eric.dumazet@gmail.com
Cc: dormando@rydia.net, preobr@google.com,
steffen.klassert@secunet.com, paulmck@linux.vnet.ibm.com,
netdev@vger.kernel.org, kcc@google.com, dvyukov@google.com,
larsbull@google.com, edumazet@google.com, brutus@google.com,
maze@google.com, alexei.starovoitov@gmail.com
Subject: Re: [PATCH net] ipv4: fix dst race in sk_dst_get()
Date: Wed, 25 Jun 2014 17:42:14 -0700 (PDT) [thread overview]
Message-ID: <20140625.174214.1193347044692011852.davem@davemloft.net> (raw)
In-Reply-To: <1403629511.3796.35.camel@edumazet-glaptop2.roam.corp.google.com>
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 24 Jun 2014 10:05:11 -0700
> From: Eric Dumazet <edumazet@google.com>
>
> When IP route cache had been removed in linux-3.6, we broke assumption
> that dst entries were all freed after rcu grace period. DST_NOCACHE
> dst were supposed to be freed from dst_release(). But it appears
> we want to keep such dst around, either in UDP sockets or tunnels.
>
> In sk_dst_get() we need to make sure dst refcount is not 0
> before incrementing it, or else we might end up freeing a dst
> twice.
>
> DST_NOCACHE set on a dst does not mean this dst can not be attached
> to a socket or a tunnel.
>
> Then, before actual freeing, we need to observe a rcu grace period
> to make sure all other cpus can catch the fact the dst is no longer
> usable.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Dormando <dormando@rydia.net>
Applied and queued up for -stable, thanks Eric.
next prev parent reply other threads:[~2014-06-26 0:42 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-06 11:29 Potential race in ip4_datagram_release_cb Alexey Preobrazhensky
2014-06-06 12:56 ` Eric Dumazet
2014-06-06 15:59 ` Alexei Starovoitov
2014-06-06 16:16 ` Eric Dumazet
2014-06-06 17:44 ` Alexei Starovoitov
2014-06-06 17:56 ` Eric Dumazet
2014-06-06 18:13 ` Alexei Starovoitov
2014-06-10 13:43 ` [PATCH] ipv4: fix a race in ip4_datagram_release_cb() Eric Dumazet
2014-06-11 0:32 ` dormando
2014-06-11 0:55 ` Eric Dumazet
2014-06-11 1:12 ` Eric Dumazet
2014-06-11 1:26 ` Eric Dumazet
2014-06-11 4:16 ` dormando
2014-06-11 5:54 ` Eric Dumazet
2014-06-11 7:20 ` dormando
2014-06-11 7:26 ` dormando
2014-06-11 7:38 ` dormando
2014-06-11 12:41 ` Eric Dumazet
2014-06-11 13:12 ` Eric Dumazet
2014-06-12 1:55 ` dormando
2014-06-12 3:43 ` Eric Dumazet
2014-06-12 4:05 ` dormando
2014-06-22 19:07 ` dormando
2014-06-23 8:33 ` Eric Dumazet
2014-06-23 8:55 ` dormando
2014-06-23 16:57 ` Dmitry Vyukov
2014-06-24 17:05 ` [PATCH net] ipv4: fix dst race in sk_dst_get() Eric Dumazet
2014-06-26 0:42 ` David Miller [this message]
2014-06-11 13:38 ` [PATCH] ipv4: fix a race in ip4_datagram_release_cb() Kostya Serebryany
2014-06-29 0:25 ` dormando
2014-06-30 6:38 ` Eric Dumazet
2014-06-30 8:15 ` dormando
2014-06-30 8:30 ` Eric Dumazet
2014-07-08 1:41 ` dormando
2014-07-08 6:47 ` Eric Dumazet
2014-07-08 7:01 ` dormando
2014-07-16 21:03 ` dormando
2014-07-25 8:11 ` dormando
2014-06-30 8:26 ` [PATCH] ipv4: irq safe sk_dst_[re]set() and ipv4_sk_update_pmtu() fix Eric Dumazet
2014-07-01 6:43 ` David Miller
2014-06-11 22:39 ` [PATCH] ipv4: fix a race in ip4_datagram_release_cb() David Miller
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