netdev - Re: Linux 3.1-rc9

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Date:	Wed, 02 Nov 2011 23:42:56 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Simon Kirby <sim@...tway.ca>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	David Miller <davem@...emloft.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Dave Jones <davej@...hat.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Ingo Molnar <mingo@...e.hu>,
	Network Development <netdev@...r.kernel.org>,
	Balazs Scheidler <bazsi@...abit.hu>,
	KOVACS Krisztian <hidden@...abit.hu>
Subject: Re: Linux 3.1-rc9

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@...tway.ca>
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
Tested-by: Eric Dumazet <eric.dumazet@...il.com>
CC: Balazs Scheidler <bazsi@...abit.hu>
CC: KOVACS Krisztian <hidden@...abit.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;
 }
--
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