Re: Linux 3.1-rc9

[Simon Kirby]

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@xxxxxxxxxx>
> Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> Tested-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
> CC: Balazs Scheidler <bazsi@xxxxxxxxxx>
> CC: KOVACS Krisztian <hidden@xxxxxxxxxx>
> ---
>  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@xxxxxxxxxx>

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

Thanks!

Simon-
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