[PATCH net] ipv4: disable BH in set_ping_group_range()

[PATCH net] ipv4: disable BH in set_ping_group_range()

[Eric Dumazet]

From: Eric Dumazet <edumazet@google.com>

In commit 4ee3bd4a8c746 ("ipv4: disable BH when changing ip local port
range") Cong added BH protection in set_local_port_range() but missed
that same fix was needed in set_ping_group_range()

Fixes: b8f1a55639e6 ("udp: Add function to make source port for UDP tunnels")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Eric Salo <salo@google.com>
---
 net/ipv4/sysctl_net_ipv4.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 1cb67de106fe..500ae4010bed 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -109,10 +109,10 @@ static void set_ping_group_range(struct ctl_table *table, kgid_t low, kgid_t hig
 	kgid_t *data = table->data;
 	struct net *net =
 		container_of(table->data, struct net, ipv4.ping_group_range.range);
-	write_seqlock(&net->ipv4.ip_local_ports.lock);
+	write_seqlock_bh(&net->ipv4.ip_local_ports.lock);
 	data[0] = low;
 	data[1] = high;
-	write_sequnlock(&net->ipv4.ip_local_ports.lock);
+	write_sequnlock_bh(&net->ipv4.ip_local_ports.lock);
 }
 
 /* Validate changes from /proc interface. */

Re: [PATCH net] ipv4: disable BH in set_ping_group_range()

[David Miller]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 20 Oct 2016 10:26:48 -0700

> From: Eric Dumazet <edumazet@google.com>
> 
> In commit 4ee3bd4a8c746 ("ipv4: disable BH when changing ip local port
> range") Cong added BH protection in set_local_port_range() but missed
> that same fix was needed in set_ping_group_range()
> 
> Fixes: b8f1a55639e6 ("udp: Add function to make source port for UDP tunnels")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Eric Salo <salo@google.com>

Applied and queued up for -stable.

Re: [PATCH net] ipv4: disable BH in set_ping_group_range()

[Cong Wang]

On Thu, Oct 20, 2016 at 10:26 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> In commit 4ee3bd4a8c746 ("ipv4: disable BH when changing ip local port
> range") Cong added BH protection in set_local_port_range() but missed
> that same fix was needed in set_ping_group_range()

Don't know why ping_group_range shares the same lock with local_port_range...
Perhaps just for saving a few bytes, but that is why I missed this place.

Re: [PATCH net] ipv4: disable BH in set_ping_group_range()

[Cong Wang]

On Thu, Oct 20, 2016 at 12:32 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Thu, Oct 20, 2016 at 10:26 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>> From: Eric Dumazet <edumazet@google.com>
>>
>> In commit 4ee3bd4a8c746 ("ipv4: disable BH when changing ip local port
>> range") Cong added BH protection in set_local_port_range() but missed
>> that same fix was needed in set_ping_group_range()
>
> Don't know why ping_group_range shares the same lock with local_port_range...
> Perhaps just for saving a few bytes, but that is why I missed this place.

Hold on... We clearly have typos there... Your fix is not correct.

Re: [PATCH net] ipv4: disable BH in set_ping_group_range()

[Cong Wang]

[-- Attachment #1: Type: text/plain, Size: 872 bytes --]

On Thu, Oct 20, 2016 at 12:40 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Thu, Oct 20, 2016 at 12:32 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> On Thu, Oct 20, 2016 at 10:26 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>>> From: Eric Dumazet <edumazet@google.com>
>>>
>>> In commit 4ee3bd4a8c746 ("ipv4: disable BH when changing ip local port
>>> range") Cong added BH protection in set_local_port_range() but missed
>>> that same fix was needed in set_ping_group_range()
>>
>> Don't know why ping_group_range shares the same lock with local_port_range...
>> Perhaps just for saving a few bytes, but that is why I missed this place.
>
> Hold on... We clearly have typos there... Your fix is not correct.

We need the attached patch, your patch should be reverted, because
unlike local_port_range we never read it in BH context, no need to bother _bh.

[-- Attachment #2: ping.diff --]
[-- Type: text/plain, Size: 1211 bytes --]

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 1cb67de..80bc36b 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -96,11 +96,11 @@ static void inet_get_ping_group_range_table(struct ctl_table *table, kgid_t *low
 		container_of(table->data, struct net, ipv4.ping_group_range.range);
 	unsigned int seq;
 	do {
-		seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
+		seq = read_seqbegin(&net->ipv4.ping_group_range.lock);
 
 		*low = data[0];
 		*high = data[1];
-	} while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
+	} while (read_seqretry(&net->ipv4.ping_group_range.lock, seq));
 }
 
 /* Update system visible IP port range */
@@ -109,10 +109,10 @@ static void set_ping_group_range(struct ctl_table *table, kgid_t low, kgid_t hig
 	kgid_t *data = table->data;
 	struct net *net =
 		container_of(table->data, struct net, ipv4.ping_group_range.range);
-	write_seqlock(&net->ipv4.ip_local_ports.lock);
+	write_seqlock(&net->ipv4.ping_group_range.lock);
 	data[0] = low;
 	data[1] = high;
-	write_sequnlock(&net->ipv4.ip_local_ports.lock);
+	write_sequnlock(&net->ipv4.ping_group_range.lock);
 }
 
 /* Validate changes from /proc interface. */

Re: [PATCH net] ipv4: disable BH in set_ping_group_range()

[Eric Dumazet]

On Thu, 2016-10-20 at 12:44 -0700, Cong Wang wrote:
> On Thu, Oct 20, 2016 at 12:40 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> > On Thu, Oct 20, 2016 at 12:32 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> >> On Thu, Oct 20, 2016 at 10:26 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> >>> From: Eric Dumazet <edumazet@google.com>
> >>>
> >>> In commit 4ee3bd4a8c746 ("ipv4: disable BH when changing ip local port
> >>> range") Cong added BH protection in set_local_port_range() but missed
> >>> that same fix was needed in set_ping_group_range()
> >>
> >> Don't know why ping_group_range shares the same lock with local_port_range...
> >> Perhaps just for saving a few bytes, but that is why I missed this place.
> >
> > Hold on... We clearly have typos there... Your fix is not correct.
> 
> We need the attached patch, your patch should be reverted, because
> unlike local_port_range we never read it in BH context, no need to bother _bh.

Well, we do not change this sysctl very often, so I am not sure why we
need different seqlocks to protect these ranges.

Seems a waste of space really (per netns)

 

Re: [PATCH net] ipv4: disable BH in set_ping_group_range()

[Cong Wang]

On Thu, Oct 20, 2016 at 1:43 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Thu, 2016-10-20 at 12:44 -0700, Cong Wang wrote:
>> On Thu, Oct 20, 2016 at 12:40 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> > On Thu, Oct 20, 2016 at 12:32 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
>> >> On Thu, Oct 20, 2016 at 10:26 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>> >>> From: Eric Dumazet <edumazet@google.com>
>> >>>
>> >>> In commit 4ee3bd4a8c746 ("ipv4: disable BH when changing ip local port
>> >>> range") Cong added BH protection in set_local_port_range() but missed
>> >>> that same fix was needed in set_ping_group_range()
>> >>
>> >> Don't know why ping_group_range shares the same lock with local_port_range...
>> >> Perhaps just for saving a few bytes, but that is why I missed this place.
>> >
>> > Hold on... We clearly have typos there... Your fix is not correct.
>>
>> We need the attached patch, your patch should be reverted, because
>> unlike local_port_range we never read it in BH context, no need to bother _bh.
>
> Well, we do not change this sysctl very often, so I am not sure why we
> need different seqlocks to protect these ranges.
>
> Seems a waste of space really (per netns)

Error prone vs. space saving, it's up to you...

But clearly current code is still broken even after your patch. I will send
a revert + previous typo fix.

Re: [PATCH net] ipv4: disable BH in set_ping_group_range()

[Eric Dumazet]

On Thu, 2016-10-20 at 14:00 -0700, Cong Wang wrote:

> Error prone vs. space saving, it's up to you...
> 
> But clearly current code is still broken even after your patch. I will send
> a revert + previous typo fix.

Yes please do.