* [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay
@ 2013-11-13 16:07 Nikolay Aleksandrov
2013-11-13 16:34 ` Nikolay Aleksandrov
` (3 more replies)
0 siblings, 4 replies; 8+ messages in thread
From: Nikolay Aleksandrov @ 2013-11-13 16:07 UTC (permalink / raw)
To: netdev
Cc: davem, Nikolay Aleksandrov, Jay Vosburgh, Andy Gospodarek,
Veaceslav Falico
This patch fixes two race conditions between bond_store_updelay/downdelay
and bond_store_miimon which could lead to division by zero as miimon can
be set to 0 while either updelay/downdelay are being set and thus miss the
zero check in the beginning, the zero div happens because updelay/downdelay
are stored as new_value / bond->params.miimon. Use rtnl to synchronize with
miimon setting.
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
---
drivers/net/bonding/bond_sysfs.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
index bc8fd36..8f8a607 100644
--- a/drivers/net/bonding/bond_sysfs.c
+++ b/drivers/net/bonding/bond_sysfs.c
@@ -701,6 +701,8 @@ static ssize_t bonding_store_downdelay(struct device *d,
int new_value, ret = count;
struct bonding *bond = to_bond(d);
+ if (!rtnl_trylock())
+ return restart_syscall();
if (!(bond->params.miimon)) {
pr_err("%s: Unable to set down delay as MII monitoring is disabled\n",
bond->dev->name);
@@ -734,6 +736,7 @@ static ssize_t bonding_store_downdelay(struct device *d,
}
out:
+ rtnl_unlock();
return ret;
}
static DEVICE_ATTR(downdelay, S_IRUGO | S_IWUSR,
@@ -756,6 +759,8 @@ static ssize_t bonding_store_updelay(struct device *d,
int new_value, ret = count;
struct bonding *bond = to_bond(d);
+ if (!rtnl_trylock())
+ return restart_syscall();
if (!(bond->params.miimon)) {
pr_err("%s: Unable to set up delay as MII monitoring is disabled\n",
bond->dev->name);
@@ -789,6 +794,7 @@ static ssize_t bonding_store_updelay(struct device *d,
}
out:
+ rtnl_unlock();
return ret;
}
static DEVICE_ATTR(updelay, S_IRUGO | S_IWUSR,
--
1.8.1.4
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay
2013-11-13 16:07 [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay Nikolay Aleksandrov
@ 2013-11-13 16:34 ` Nikolay Aleksandrov
2013-11-13 17:03 ` Eric Dumazet
` (2 subsequent siblings)
3 siblings, 0 replies; 8+ messages in thread
From: Nikolay Aleksandrov @ 2013-11-13 16:34 UTC (permalink / raw)
To: Nikolay Aleksandrov, netdev
Cc: davem, Jay Vosburgh, Andy Gospodarek, Veaceslav Falico
On 11/13/2013 05:07 PM, Nikolay Aleksandrov wrote:
> This patch fixes two race conditions between bond_store_updelay/downdelay
> and bond_store_miimon which could lead to division by zero as miimon can
> be set to 0 while either updelay/downdelay are being set and thus miss the
> zero check in the beginning, the zero div happens because updelay/downdelay
> are stored as new_value / bond->params.miimon. Use rtnl to synchronize with
> miimon setting.
>
> CC: Jay Vosburgh <fubar@us.ibm.com>
> CC: Andy Gospodarek <andy@greyhouse.net>
> CC: Veaceslav Falico <vfalico@redhat.com>
> Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
> ---
A little addition: these can also race with anything that sets miimon to 0,
currently beside store_miimon only store_arp_interval does that. But that is
also fixed because store_arp_interval uses rtnl.
Cheers,
Nik
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay
2013-11-13 16:07 [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay Nikolay Aleksandrov
2013-11-13 16:34 ` Nikolay Aleksandrov
@ 2013-11-13 17:03 ` Eric Dumazet
2013-11-13 17:06 ` Nikolay Aleksandrov
2013-11-14 10:17 ` Veaceslav Falico
2013-11-14 21:29 ` David Miller
3 siblings, 1 reply; 8+ messages in thread
From: Eric Dumazet @ 2013-11-13 17:03 UTC (permalink / raw)
To: Nikolay Aleksandrov
Cc: netdev, davem, Jay Vosburgh, Andy Gospodarek, Veaceslav Falico
On Wed, 2013-11-13 at 17:07 +0100, Nikolay Aleksandrov wrote:
> This patch fixes two race conditions between bond_store_updelay/downdelay
> and bond_store_miimon which could lead to division by zero as miimon can
> be set to 0 while either updelay/downdelay are being set and thus miss the
> zero check in the beginning, the zero div happens because updelay/downdelay
> are stored as new_value / bond->params.miimon. Use rtnl to synchronize with
> miimon setting.
It seems a bit heavy duty to take rtnl for this.
Using ACCESS_ONCE() in bonding_store_updelay()/bonding_store_downdelay()
should be enough ?
int miimon = ACCESS_ONCE(bond->params.miimon);
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay
2013-11-13 17:03 ` Eric Dumazet
@ 2013-11-13 17:06 ` Nikolay Aleksandrov
2013-11-13 17:38 ` Eric Dumazet
2013-11-14 1:50 ` Ding Tianhong
0 siblings, 2 replies; 8+ messages in thread
From: Nikolay Aleksandrov @ 2013-11-13 17:06 UTC (permalink / raw)
To: Eric Dumazet
Cc: netdev, davem, Jay Vosburgh, Andy Gospodarek, Veaceslav Falico
On 11/13/2013 06:03 PM, Eric Dumazet wrote:
> On Wed, 2013-11-13 at 17:07 +0100, Nikolay Aleksandrov wrote:
>> This patch fixes two race conditions between bond_store_updelay/downdelay
>> and bond_store_miimon which could lead to division by zero as miimon can
>> be set to 0 while either updelay/downdelay are being set and thus miss the
>> zero check in the beginning, the zero div happens because updelay/downdelay
>> are stored as new_value / bond->params.miimon. Use rtnl to synchronize with
>> miimon setting.
>
> It seems a bit heavy duty to take rtnl for this.
>
> Using ACCESS_ONCE() in bonding_store_updelay()/bonding_store_downdelay()
> should be enough ?
>
> int miimon = ACCESS_ONCE(bond->params.miimon);
>
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
Hi Eric,
I thought about this version too, but downdelay/updelay can be changed in other
places (e.g., store_miimon) and the resulting downdelay/updelay value might not
be the right one.
Correct me if I'm wrong, but this is what I have in mind (miimon = 100, updelay
= 200):
set miimon to 300 and concurrently set updelay to 400, we might endup leaving
updelay to 400 because the old value of miimon is used in the calculation in
store_updelay even though when changing miimon updelay/downdelay get adjusted,
they might get adjusted by store_updelay/downdelay to a wrong value afterwards.
Nik
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay
2013-11-13 17:06 ` Nikolay Aleksandrov
@ 2013-11-13 17:38 ` Eric Dumazet
2013-11-14 1:50 ` Ding Tianhong
1 sibling, 0 replies; 8+ messages in thread
From: Eric Dumazet @ 2013-11-13 17:38 UTC (permalink / raw)
To: Nikolay Aleksandrov
Cc: netdev, davem, Jay Vosburgh, Andy Gospodarek, Veaceslav Falico
On Wed, 2013-11-13 at 18:06 +0100, Nikolay Aleksandrov wrote:
> I thought about this version too, but downdelay/updelay can be changed in other
> places (e.g., store_miimon) and the resulting downdelay/updelay value might not
> be the right one.
> Correct me if I'm wrong, but this is what I have in mind (miimon = 100, updelay
> = 200):
> set miimon to 300 and concurrently set updelay to 400, we might endup leaving
> updelay to 400 because the old value of miimon is used in the calculation in
> store_updelay even though when changing miimon updelay/downdelay get adjusted,
> they might get adjusted by store_updelay/downdelay to a wrong value afterwards.
OK then ;)
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay
2013-11-13 17:06 ` Nikolay Aleksandrov
2013-11-13 17:38 ` Eric Dumazet
@ 2013-11-14 1:50 ` Ding Tianhong
1 sibling, 0 replies; 8+ messages in thread
From: Ding Tianhong @ 2013-11-14 1:50 UTC (permalink / raw)
To: Nikolay Aleksandrov, Eric Dumazet
Cc: netdev, davem, Jay Vosburgh, Andy Gospodarek, Veaceslav Falico
On 2013/11/14 1:06, Nikolay Aleksandrov wrote:
> On 11/13/2013 06:03 PM, Eric Dumazet wrote:
>> On Wed, 2013-11-13 at 17:07 +0100, Nikolay Aleksandrov wrote:
>>> This patch fixes two race conditions between bond_store_updelay/downdelay
>>> and bond_store_miimon which could lead to division by zero as miimon can
>>> be set to 0 while either updelay/downdelay are being set and thus miss the
>>> zero check in the beginning, the zero div happens because updelay/downdelay
>>> are stored as new_value / bond->params.miimon. Use rtnl to synchronize with
>>> miimon setting.
>>
>> It seems a bit heavy duty to take rtnl for this.
>>
>> Using ACCESS_ONCE() in bonding_store_updelay()/bonding_store_downdelay()
>> should be enough ?
>>
>> int miimon = ACCESS_ONCE(bond->params.miimon);
>>
>>
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe netdev" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>>
> Hi Eric,
> I thought about this version too, but downdelay/updelay can be changed in other
> places (e.g., store_miimon) and the resulting downdelay/updelay value might not
> be the right one.
> Correct me if I'm wrong, but this is what I have in mind (miimon = 100, updelay
> = 200):
> set miimon to 300 and concurrently set updelay to 400, we might endup leaving
> updelay to 400 because the old value of miimon is used in the calculation in
> store_updelay even though when changing miimon updelay/downdelay get adjusted,
> they might get adjusted by store_updelay/downdelay to a wrong value afterwards.
>
> Nik
>
>
agree, set miimon and set updelay may conflict.
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay
2013-11-13 16:07 [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay Nikolay Aleksandrov
2013-11-13 16:34 ` Nikolay Aleksandrov
2013-11-13 17:03 ` Eric Dumazet
@ 2013-11-14 10:17 ` Veaceslav Falico
2013-11-14 21:29 ` David Miller
3 siblings, 0 replies; 8+ messages in thread
From: Veaceslav Falico @ 2013-11-14 10:17 UTC (permalink / raw)
To: Nikolay Aleksandrov; +Cc: netdev, davem, Jay Vosburgh, Andy Gospodarek
On Wed, Nov 13, 2013 at 05:07:46PM +0100, Nikolay Aleksandrov wrote:
>This patch fixes two race conditions between bond_store_updelay/downdelay
>and bond_store_miimon which could lead to division by zero as miimon can
>be set to 0 while either updelay/downdelay are being set and thus miss the
>zero check in the beginning, the zero div happens because updelay/downdelay
>are stored as new_value / bond->params.miimon. Use rtnl to synchronize with
>miimon setting.
>
>CC: Jay Vosburgh <fubar@us.ibm.com>
>CC: Andy Gospodarek <andy@greyhouse.net>
>CC: Veaceslav Falico <vfalico@redhat.com>
>Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Nice, thanks! :)
Acked-by: Veaceslav Falico <vfalico@redhat.com>
>---
> drivers/net/bonding/bond_sysfs.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
>diff --git a/drivers/net/bonding/bond_sysfs.c b/drivers/net/bonding/bond_sysfs.c
>index bc8fd36..8f8a607 100644
>--- a/drivers/net/bonding/bond_sysfs.c
>+++ b/drivers/net/bonding/bond_sysfs.c
>@@ -701,6 +701,8 @@ static ssize_t bonding_store_downdelay(struct device *d,
> int new_value, ret = count;
> struct bonding *bond = to_bond(d);
>
>+ if (!rtnl_trylock())
>+ return restart_syscall();
> if (!(bond->params.miimon)) {
> pr_err("%s: Unable to set down delay as MII monitoring is disabled\n",
> bond->dev->name);
>@@ -734,6 +736,7 @@ static ssize_t bonding_store_downdelay(struct device *d,
> }
>
> out:
>+ rtnl_unlock();
> return ret;
> }
> static DEVICE_ATTR(downdelay, S_IRUGO | S_IWUSR,
>@@ -756,6 +759,8 @@ static ssize_t bonding_store_updelay(struct device *d,
> int new_value, ret = count;
> struct bonding *bond = to_bond(d);
>
>+ if (!rtnl_trylock())
>+ return restart_syscall();
> if (!(bond->params.miimon)) {
> pr_err("%s: Unable to set up delay as MII monitoring is disabled\n",
> bond->dev->name);
>@@ -789,6 +794,7 @@ static ssize_t bonding_store_updelay(struct device *d,
> }
>
> out:
>+ rtnl_unlock();
> return ret;
> }
> static DEVICE_ATTR(updelay, S_IRUGO | S_IWUSR,
>--
>1.8.1.4
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay
2013-11-13 16:07 [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay Nikolay Aleksandrov
` (2 preceding siblings ...)
2013-11-14 10:17 ` Veaceslav Falico
@ 2013-11-14 21:29 ` David Miller
3 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2013-11-14 21:29 UTC (permalink / raw)
To: nikolay; +Cc: netdev, fubar, andy, vfalico
From: Nikolay Aleksandrov <nikolay@redhat.com>
Date: Wed, 13 Nov 2013 17:07:46 +0100
> This patch fixes two race conditions between bond_store_updelay/downdelay
> and bond_store_miimon which could lead to division by zero as miimon can
> be set to 0 while either updelay/downdelay are being set and thus miss the
> zero check in the beginning, the zero div happens because updelay/downdelay
> are stored as new_value / bond->params.miimon. Use rtnl to synchronize with
> miimon setting.
>
> CC: Jay Vosburgh <fubar@us.ibm.com>
> CC: Andy Gospodarek <andy@greyhouse.net>
> CC: Veaceslav Falico <vfalico@redhat.com>
> Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Applied and queued up for -stable, thanks.
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2013-11-14 21:29 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-11-13 16:07 [PATCH net] bonding: fix two race conditions in bond_store_updelay/downdelay Nikolay Aleksandrov
2013-11-13 16:34 ` Nikolay Aleksandrov
2013-11-13 17:03 ` Eric Dumazet
2013-11-13 17:06 ` Nikolay Aleksandrov
2013-11-13 17:38 ` Eric Dumazet
2013-11-14 1:50 ` Ding Tianhong
2013-11-14 10:17 ` Veaceslav Falico
2013-11-14 21:29 ` David Miller
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