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SubjectRe: Linux 3.1-rc9
On Wed, Nov 02, 2011 at 11:42:56PM +0100, Eric Dumazet wrote:

> On 02/11/2011 20:16, Simon Kirby wrote:
>
>
> > Actually, we have an anti-abuse daemon that injects blackhole routes, so
> > this makes sense. (The daemon was written before ipsets were merged and
> > normal netfilter rules make it fall over under attack.)
> >
> > I'll try with this patch. Thanks!
> >
>
>
> Thanks !
>
> Here is the official submission, please add your 'Tested-by' signature
> when you can confirm problem goes away.
>
> (It did here, when I injected random NULL returns from
> inet_csk_route_child_sock(), so I am confident this is the problem you hit )
>
> [PATCH] net: add missing bh_unlock_sock() calls
>
> Simon Kirby reported lockdep warnings and following messages :
>
> [104661.897577] huh, entered softirq 3 NET_RX ffffffff81613740
> preempt_count 00000101, exited with 00000102?
>
> [104661.923653] huh, entered softirq 3 NET_RX ffffffff81613740
> preempt_count 00000101, exited with 00000102?
>
> Problem comes from commit 0e734419
> (ipv4: Use inet_csk_route_child_sock() in DCCP and TCP.)
>
> If inet_csk_route_child_sock() returns NULL, we should release socket
> lock before freeing it.
>
> Another lock imbalance exists if __inet_inherit_port() returns an error
> since commit 093d282321da ( tproxy: fix hash locking issue when using
> port redirection in __inet_inherit_port()) a backport is also needed for
> >= 2.6.37 kernels.
>
> Reported-by: Dimon Kirby <sim@hostway.ca>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> Tested-by: Eric Dumazet <eric.dumazet@gmail.com>
> CC: Balazs Scheidler <bazsi@balabit.hu>
> CC: KOVACS Krisztian <hidden@balabit.hu>
> ---
> net/dccp/ipv4.c | 1 +
> net/ipv4/tcp_ipv4.c | 1 +
> 2 files changed, 2 insertions(+)
>
> diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
> index 332639b..90a919a 100644
> --- a/net/dccp/ipv4.c
> +++ b/net/dccp/ipv4.c
> @@ -433,6 +433,7 @@ exit:
> NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
> return NULL;
> put_and_exit:
> + bh_unlock_sock(newsk);
> sock_put(newsk);
> goto exit;
> }
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 0ea10ee..683d97a 100644
> --- a/net/ipv4/tcp_ipv4.c
> +++ b/net/ipv4/tcp_ipv4.c
> @@ -1510,6 +1510,7 @@ exit:
> NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
> return NULL;
> put_and_exit:
> + bh_unlock_sock(newsk);
> sock_put(newsk);
> goto exit;
> }

Tested-by: Simon Kirby <sim@hostway.ca>

I tried many times, with route unreach/blackhole, and could not reproduce
the issue with this patch applied.

Thanks!

Simon-


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