[PATCH] [AX25] circular locking with AX25 connection timeout

[PATCH] [AX25] circular locking with AX25 connection timeout

[Bernard Pidoux]

[-- Attachment #1: Type: text/plain, Size: 136 bytes --]

Hi,

This patch cancels a circular locking conflict that appeared with a 
timeout of an AX25 connection.

signed off by Jarek Poplawski

[-- Attachment #2: rose-2.6.24-rc5.patch3 --]
[-- Type: text/plain, Size: 472 bytes --]

--- linux-2.6.24-rc5/net/ax25/ax25_subr.c	2007-12-11 04:48:43.000000000 +0100
+++ b/net/ax25/ax25_subr.c	2007-12-14 14:30:02.000000000 +0100
@@ -279,6 +279,7 @@
 	ax25_link_failed(ax25, reason);
 
 	if (ax25->sk != NULL) {
+		local_bh_disable();
 		bh_lock_sock(ax25->sk);
 		ax25->sk->sk_state     = TCP_CLOSE;
 		ax25->sk->sk_err       = reason;
@@ -288,5 +289,6 @@
 			sock_set_flag(ax25->sk, SOCK_DEAD);
 		}
 		bh_unlock_sock(ax25->sk);
+		local_bh_enable(); 
 	}
 }

[PATCH take2] [AX25] circular locking with AX25 connection timeout

[Jarek Poplawski]

On Fri, Dec 14, 2007 at 11:29:28PM +0100, Bernard Pidoux wrote:
> Hi,
>
> This patch cancels a circular locking conflict that appeared with a timeout 
> of an AX25 connection.
>
> signed off by Jarek Poplawski

One spurious space less here, and maybe a few more words to the changelog.

Regards,
Jarek P.
---------------->

Subject: [PATCH] [NET] AX25: locking dependencies fix in ax25_disconnect

Bernard Pidoux reported these lockdep warnings:

[ INFO: possible irq lock inversion dependency detected ]
2.6.23.1 #1
---------------------------------------------------------
fpac/4933 just changed the state of lock:
 (slock-AF_AX25){--..}, at: [<d8be3312>] ax25_disconnect+0x46/0xaf
 [ax25]
 but this lock was taken by another, soft-irq-safe lock in the past:
  (ax25_list_lock){-+..}

  and interrupts could create inverse lock ordering between them.
  [...]

[ INFO: inconsistent lock state ]
2.6.23.1 #1
---------------------------------
inconsistent {in-softirq-W} -> {softirq-on-W} usage.
ax25_call/4005 [HC0[0]:SC0[0]:HE1:SE1] takes:
 (slock-AF_AX25){-+..}, at: [<d8b79312>] ax25_disconnect+0x46/0xaf [ax25]
 [...]

This means slock-AF_AX25 could be taken both from softirq and process
context with softirqs enabled, so it's endangered itself, but also makes
ax25_list_lock vulnerable. It was not 100% verified if the real lockup
can happen, but this fix isn't very costly and looks safe anyway.
(It was tested by Bernard with 2.6.23.9 and 2.6.24-rc5 kernels.)


Reported_by: Bernard Pidoux <pidoux@ccr.jussieu.fr>
Tested_by: Bernard Pidoux <pidoux@ccr.jussieu.fr>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>

---

diff -Nurp linux-2.6.24-rc2-/net/ax25/ax25_subr.c linux-2.6.24-rc2+/net/ax25/ax25_subr.c
--- linux-2.6.24-rc2-/net/ax25/ax25_subr.c	2007-10-09 22:31:38.000000000 +0200
+++ linux-2.6.24-rc2+/net/ax25/ax25_subr.c	2007-11-28 11:51:12.000000000 +0100
@@ -279,6 +279,7 @@ void ax25_disconnect(ax25_cb *ax25, int 
 	ax25_link_failed(ax25, reason);
 
 	if (ax25->sk != NULL) {
+		local_bh_disable();
 		bh_lock_sock(ax25->sk);
 		ax25->sk->sk_state     = TCP_CLOSE;
 		ax25->sk->sk_err       = reason;
@@ -288,5 +289,6 @@ void ax25_disconnect(ax25_cb *ax25, int 
 			sock_set_flag(ax25->sk, SOCK_DEAD);
 		}
 		bh_unlock_sock(ax25->sk);
+		local_bh_enable();
 	}
 }

[BUG] lack of /proc/net/ax25 with 2.6.24-rc5

[Bernard Pidoux]

With 2.6.24-rc5 there is no /proc/net/ax25

Here is an extract from dmesg after boot :

=======================
sysctl table check failed: /net/ax25/ax0/ax25_default_mode .3.9.1.2 
Unknown sysctl binary path
Pid: 2936, comm: kissattach Not tainted 2.6.24-rc5 #1
  [<c012ca6a>] set_fail+0x3b/0x43
  [<c012ce7a>] sysctl_check_table+0x408/0x456
  [<c012ce8e>] sysctl_check_table+0x41c/0x456
  [<c012ce8e>] sysctl_check_table+0x41c/0x456
  [<c02ac64a>] _spin_unlock+0x14/0x1c
  [<c012ce8e>] sysctl_check_table+0x41c/0x456
  [<c011e681>] sysctl_set_parent+0x19/0x2a
  [<c011f55c>] register_sysctl_table+0x45/0x85
  [<d8be9d26>] ax25_register_sysctl+0x112/0x11c [ax25]
  [<d8be6c76>] ax25_device_event+0x2e/0x90 [ax25]
  [<c012c560>] notifier_call_chain+0x2a/0x47
  [<c012c59f>] raw_notifier_call_chain+0x17/0x1a
  [<c0259290>] dev_open+0x6f/0x75
  [<c0257ee7>] dev_change_flags+0x9c/0x148
  [<c0256ab3>] __dev_get_by_name+0x68/0x73
  [<c0292307>] devinet_ioctl+0x22e/0x53b
  [<c0259074>] dev_ioctl+0x472/0x5ba
  [<c024d4ba>] sock_ioctl+0x1aa/0x1cf
  [<c024d310>] sock_ioctl+0x0/0x1cf
  [<c016bc19>] do_ioctl+0x19/0x4c
  [<c016be40>] vfs_ioctl+0x1f4/0x20b
  [<c0103d01>] sysenter_past_esp+0x9a/0xa9
  [<c016be9c>] sys_ioctl+0x45/0x5d
  [<c0103cc6>] sysenter_past_esp+0x5f/0xa9
  =======================
sysctl table check failed: /net/ax25/ax0/backoff_type .3.9.1.3 Unknown 
sysctl binary path
(...) truncated
  =======================
sysctl table check failed: /net/ax25/ax0/connect_mode .3.9.1.4 Unknown 
sysctl binary path
(...)
  =======================
sysctl table check failed: /net/ax25/ax0/standard_window_size .3.9.1.5 
Unknown sysctl binary path
  =======================
(...)

and so on ...



Bernard Pidoux
f6bvp@amsat.org

Re: [PATCH take2] [AX25] circular locking with AX25 connection timeout

[David Miller]

From: Jarek Poplawski <jarkao2@gmail.com>
Date: Sat, 15 Dec 2007 11:18:10 +0100

> On Fri, Dec 14, 2007 at 11:29:28PM +0100, Bernard Pidoux wrote:
> > Hi,
> >
> > This patch cancels a circular locking conflict that appeared with a timeout 
> > of an AX25 connection.
> >
> > signed off by Jarek Poplawski
> 
> One spurious space less here, and maybe a few more words to the changelog.

Patch applied, thanks Jarek.

Re: [BUG] lack of /proc/net/ax25 with 2.6.24-rc5

[Rafael J. Wysocki]

On Sunday, 16 of December 2007, Bernard Pidoux wrote:
> With 2.6.24-rc5 there is no /proc/net/ax25

FYI, I've created a Bugzilla entry for this issue at:
http://bugzilla.kernel.org/show_bug.cgi?id=9589

Please add your address to the CC list in there.

Thanks,
Rafael


> Here is an extract from dmesg after boot :
> 
> =======================
> sysctl table check failed: /net/ax25/ax0/ax25_default_mode .3.9.1.2 
> Unknown sysctl binary path
> Pid: 2936, comm: kissattach Not tainted 2.6.24-rc5 #1
>   [<c012ca6a>] set_fail+0x3b/0x43
>   [<c012ce7a>] sysctl_check_table+0x408/0x456
>   [<c012ce8e>] sysctl_check_table+0x41c/0x456
>   [<c012ce8e>] sysctl_check_table+0x41c/0x456
>   [<c02ac64a>] _spin_unlock+0x14/0x1c
>   [<c012ce8e>] sysctl_check_table+0x41c/0x456
>   [<c011e681>] sysctl_set_parent+0x19/0x2a
>   [<c011f55c>] register_sysctl_table+0x45/0x85
>   [<d8be9d26>] ax25_register_sysctl+0x112/0x11c [ax25]
>   [<d8be6c76>] ax25_device_event+0x2e/0x90 [ax25]
>   [<c012c560>] notifier_call_chain+0x2a/0x47
>   [<c012c59f>] raw_notifier_call_chain+0x17/0x1a
>   [<c0259290>] dev_open+0x6f/0x75
>   [<c0257ee7>] dev_change_flags+0x9c/0x148
>   [<c0256ab3>] __dev_get_by_name+0x68/0x73
>   [<c0292307>] devinet_ioctl+0x22e/0x53b
>   [<c0259074>] dev_ioctl+0x472/0x5ba
>   [<c024d4ba>] sock_ioctl+0x1aa/0x1cf
>   [<c024d310>] sock_ioctl+0x0/0x1cf
>   [<c016bc19>] do_ioctl+0x19/0x4c
>   [<c016be40>] vfs_ioctl+0x1f4/0x20b
>   [<c0103d01>] sysenter_past_esp+0x9a/0xa9
>   [<c016be9c>] sys_ioctl+0x45/0x5d
>   [<c0103cc6>] sysenter_past_esp+0x5f/0xa9
>   =======================
> sysctl table check failed: /net/ax25/ax0/backoff_type .3.9.1.3 Unknown 
> sysctl binary path
> (...) truncated
>   =======================
> sysctl table check failed: /net/ax25/ax0/connect_mode .3.9.1.4 Unknown 
> sysctl binary path
> (...)
>   =======================
> sysctl table check failed: /net/ax25/ax0/standard_window_size .3.9.1.5 
> Unknown sysctl binary path
>   =======================
> (...)
> 
> and so on ...
> 
> 
> 
> Bernard Pidoux
> f6bvp@amsat.org
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 
> 



-- 
"Premature optimization is the root of all evil." - Donald Knuth

[PATCH] sysctl: Fix ax25 checks

[Eric W. Biederman]

Bernard Pidoux <pidoux@ccr.jussieu.fr> writes:

> With 2.6.24-rc5 there is no /proc/net/ax25

/proc/sys/net/ax25?

> Here is an extract from dmesg after boot :

Groan.  I thought I had found the last of the bugs with
my sysctl sanity checks.  I guess you actually have to
use ax25 for this bug to show up.

Thank you for catching this. 

> =======================
> sysctl table check failed: /net/ax25/ax0/ax25_default_mode .3.9.1.2 Unknown
> sysctl binary path
> Pid: 2936, comm: kissattach Not tainted 2.6.24-rc5 #1
>  [<c012ca6a>] set_fail+0x3b/0x43
>  [<c012ce7a>] sysctl_check_table+0x408/0x456
>  [<c012ce8e>] sysctl_check_table+0x41c/0x456
>  [<c012ce8e>] sysctl_check_table+0x41c/0x456
>  [<c02ac64a>] _spin_unlock+0x14/0x1c
>  [<c012ce8e>] sysctl_check_table+0x41c/0x456
>  [<c011e681>] sysctl_set_parent+0x19/0x2a
>  [<c011f55c>] register_sysctl_table+0x45/0x85
>  [<d8be9d26>] ax25_register_sysctl+0x112/0x11c [ax25]
>  [<d8be6c76>] ax25_device_event+0x2e/0x90 [ax25]
>  [<c012c560>] notifier_call_chain+0x2a/0x47
>  [<c012c59f>] raw_notifier_call_chain+0x17/0x1a
>  [<c0259290>] dev_open+0x6f/0x75
>  [<c0257ee7>] dev_change_flags+0x9c/0x148
>  [<c0256ab3>] __dev_get_by_name+0x68/0x73
>  [<c0292307>] devinet_ioctl+0x22e/0x53b
>  [<c0259074>] dev_ioctl+0x472/0x5ba
>  [<c024d4ba>] sock_ioctl+0x1aa/0x1cf
>  [<c024d310>] sock_ioctl+0x0/0x1cf
>  [<c016bc19>] do_ioctl+0x19/0x4c
>  [<c016be40>] vfs_ioctl+0x1f4/0x20b
>  [<c0103d01>] sysenter_past_esp+0x9a/0xa9
>  [<c016be9c>] sys_ioctl+0x45/0x5d
>  [<c0103cc6>] sysenter_past_esp+0x5f/0xa9
>  =======================
> sysctl table check failed: /net/ax25/ax0/backoff_type .3.9.1.3 Unknown sysctl
> binary path
> (...) truncated
>  =======================
> sysctl table check failed: /net/ax25/ax0/connect_mode .3.9.1.4 Unknown sysctl
> binary path
> (...)
>  =======================
> sysctl table check failed: /net/ax25/ax0/standard_window_size .3.9.1.5 Unknown
> sysctl binary path
>  =======================
> (...)
>
> and so on ...
>

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
 kernel/sysctl_check.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c
index bed939f..a68425a 100644
--- a/kernel/sysctl_check.c
+++ b/kernel/sysctl_check.c
@@ -428,7 +428,7 @@ static struct trans_ctl_table trans_net_netrom_table[] = {
 	{}
 };
 
-static struct trans_ctl_table trans_net_ax25_table[] = {
+static struct trans_ctl_table trans_net_ax25_param_table[] = {
 	{ NET_AX25_IP_DEFAULT_MODE,	"ip_default_mode" },
 	{ NET_AX25_DEFAULT_MODE,	"ax25_default_mode" },
 	{ NET_AX25_BACKOFF_TYPE,	"backoff_type" },
@@ -446,6 +446,11 @@ static struct trans_ctl_table trans_net_ax25_table[] = {
 	{}
 };
 
+static struct trans_ctl_table trans_net_ax25_table[] = {
+	{ 0, NULL, trans_net_ax25_param_table },
+	{}
+};
+
 static struct trans_ctl_table trans_net_bridge_table[] = {
 	{ NET_BRIDGE_NF_CALL_ARPTABLES,		"bridge-nf-call-arptables" },
 	{ NET_BRIDGE_NF_CALL_IPTABLES,		"bridge-nf-call-iptables" },
-- 
1.5.3.rc6.17.g1911

Re: [PATCH] sysctl: Fix ax25 checks

[Bernard Pidoux]

Eric,

I applied your patch and now I have all /proc/sys/net/ax25
created and initialized as before.

Thanks.

Bernard Pidoux




Eric W. Biederman wrote:
> Bernard Pidoux <pidoux@ccr.jussieu.fr> writes:
> 
>> With 2.6.24-rc5 there is no /proc/net/ax25
> 
> /proc/sys/net/ax25?
> 
>> Here is an extract from dmesg after boot :
> 
> Groan.  I thought I had found the last of the bugs with
> my sysctl sanity checks.  I guess you actually have to
> use ax25 for this bug to show up.
> 
> Thank you for catching this. 
> 
>> =======================
>> sysctl table check failed: /net/ax25/ax0/ax25_default_mode .3.9.1.2 Unknown
>> sysctl binary path
>> Pid: 2936, comm: kissattach Not tainted 2.6.24-rc5 #1
>>  [<c012ca6a>] set_fail+0x3b/0x43
>>  [<c012ce7a>] sysctl_check_table+0x408/0x456
>>  [<c012ce8e>] sysctl_check_table+0x41c/0x456
>>  [<c012ce8e>] sysctl_check_table+0x41c/0x456
>>  [<c02ac64a>] _spin_unlock+0x14/0x1c
>>  [<c012ce8e>] sysctl_check_table+0x41c/0x456
>>  [<c011e681>] sysctl_set_parent+0x19/0x2a
>>  [<c011f55c>] register_sysctl_table+0x45/0x85
>>  [<d8be9d26>] ax25_register_sysctl+0x112/0x11c [ax25]
>>  [<d8be6c76>] ax25_device_event+0x2e/0x90 [ax25]
>>  [<c012c560>] notifier_call_chain+0x2a/0x47
>>  [<c012c59f>] raw_notifier_call_chain+0x17/0x1a
>>  [<c0259290>] dev_open+0x6f/0x75
>>  [<c0257ee7>] dev_change_flags+0x9c/0x148
>>  [<c0256ab3>] __dev_get_by_name+0x68/0x73
>>  [<c0292307>] devinet_ioctl+0x22e/0x53b
>>  [<c0259074>] dev_ioctl+0x472/0x5ba
>>  [<c024d4ba>] sock_ioctl+0x1aa/0x1cf
>>  [<c024d310>] sock_ioctl+0x0/0x1cf
>>  [<c016bc19>] do_ioctl+0x19/0x4c
>>  [<c016be40>] vfs_ioctl+0x1f4/0x20b
>>  [<c0103d01>] sysenter_past_esp+0x9a/0xa9
>>  [<c016be9c>] sys_ioctl+0x45/0x5d
>>  [<c0103cc6>] sysenter_past_esp+0x5f/0xa9
>>  =======================
>> sysctl table check failed: /net/ax25/ax0/backoff_type .3.9.1.3 Unknown sysctl
>> binary path
>> (...) truncated
>>  =======================
>> sysctl table check failed: /net/ax25/ax0/connect_mode .3.9.1.4 Unknown sysctl
>> binary path
>> (...)
>>  =======================
>> sysctl table check failed: /net/ax25/ax0/standard_window_size .3.9.1.5 Unknown
>> sysctl binary path
>>  =======================
>> (...)
>>
>> and so on ...
>>
> 
> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
> ---
>  kernel/sysctl_check.c |    7 ++++++-
>  1 files changed, 6 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/sysctl_check.c b/kernel/sysctl_check.c
> index bed939f..a68425a 100644
> --- a/kernel/sysctl_check.c
> +++ b/kernel/sysctl_check.c
> @@ -428,7 +428,7 @@ static struct trans_ctl_table trans_net_netrom_table[] = {
>  	{}
>  };
>  
> -static struct trans_ctl_table trans_net_ax25_table[] = {
> +static struct trans_ctl_table trans_net_ax25_param_table[] = {
>  	{ NET_AX25_IP_DEFAULT_MODE,	"ip_default_mode" },
>  	{ NET_AX25_DEFAULT_MODE,	"ax25_default_mode" },
>  	{ NET_AX25_BACKOFF_TYPE,	"backoff_type" },
> @@ -446,6 +446,11 @@ static struct trans_ctl_table trans_net_ax25_table[] = {
>  	{}
>  };
>  
> +static struct trans_ctl_table trans_net_ax25_table[] = {
> +	{ 0, NULL, trans_net_ax25_param_table },
> +	{}
> +};
> +
>  static struct trans_ctl_table trans_net_bridge_table[] = {
>  	{ NET_BRIDGE_NF_CALL_ARPTABLES,		"bridge-nf-call-arptables" },
>  	{ NET_BRIDGE_NF_CALL_IPTABLES,		"bridge-nf-call-iptables" },

Re: [PATCH] sysctl: Fix ax25 checks

[Eric W. Biederman]

Bernard Pidoux <pidoux@ccr.jussieu.fr> writes:

> Eric,
>
> I applied your patch and now I have all /proc/sys/net/ax25
> created and initialized as before.

Thanks for reporting this.

Eric

Re: [PATCH] sysctl: Fix ax25 checks

[David Miller]

From: ebiederm@xmission.com (Eric W. Biederman)
Date: Mon, 17 Dec 2007 15:44:08 -0700

> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

Applied, thanks Eric.