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* [PATCH net-next] ipv4: Fix refcount warning for new fib_info
@ 2021-08-02 16:02 David Ahern
  2021-08-02 17:58 ` Matthieu Baerts
  0 siblings, 1 reply; 5+ messages in thread
From: David Ahern @ 2021-08-02 16:02 UTC (permalink / raw)
  To: netdev, kuba, davem; +Cc: ciorneiioana, David Ahern, Yajun Deng

Ioana reported a refcount warning when booting over NFS:

[    5.042532] ------------[ cut here ]------------
[    5.047184] refcount_t: addition on 0; use-after-free.
[    5.052324] WARNING: CPU: 7 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0xa4/0x150
...
[    5.167201] Call trace:
[    5.169635]  refcount_warn_saturate+0xa4/0x150
[    5.174067]  fib_create_info+0xc00/0xc90
[    5.177982]  fib_table_insert+0x8c/0x620
[    5.181893]  fib_magic.isra.0+0x110/0x11c
[    5.185891]  fib_add_ifaddr+0xb8/0x190
[    5.189629]  fib_inetaddr_event+0x8c/0x140

fib_treeref needs to be set after kzalloc. The old code had a ++ which
led to the confusion when the int was replaced by a refcount_t.

Fixes: 79976892f7ea ("net: convert fib_treeref from int to refcount_t")
Signed-off-by: David Ahern <dsahern@kernel.org>
Reported-by: Ioana Ciornei <ciorneiioana@gmail.com>
Cc: Yajun Deng <yajun.deng@linux.dev>
---
 net/ipv4/fib_semantics.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index fa19f4cdf3a4..f29feb7772da 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1551,7 +1551,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
 		return ofi;
 	}
 
-	refcount_inc(&fi->fib_treeref);
+	refcount_set(&fi->fib_treeref, 1);
 	refcount_set(&fi->fib_clntref, 1);
 	spin_lock_bh(&fib_info_lock);
 	hlist_add_head(&fi->fib_hash,
-- 
2.24.3 (Apple Git-128)


^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH net-next] ipv4: Fix refcount warning for new fib_info
  2021-08-02 16:02 [PATCH net-next] ipv4: Fix refcount warning for new fib_info David Ahern
@ 2021-08-02 17:58 ` Matthieu Baerts
  2021-08-02 18:04   ` David Ahern
  0 siblings, 1 reply; 5+ messages in thread
From: Matthieu Baerts @ 2021-08-02 17:58 UTC (permalink / raw)
  To: David Ahern; +Cc: ciorneiioana, Yajun Deng, netdev, davem, kuba

Hi David,

On 02/08/2021 18:02, David Ahern wrote:
> Ioana reported a refcount warning when booting over NFS:
> 
> [    5.042532] ------------[ cut here ]------------
> [    5.047184] refcount_t: addition on 0; use-after-free.
> [    5.052324] WARNING: CPU: 7 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0xa4/0x150
> ...
> [    5.167201] Call trace:
> [    5.169635]  refcount_warn_saturate+0xa4/0x150
> [    5.174067]  fib_create_info+0xc00/0xc90
> [    5.177982]  fib_table_insert+0x8c/0x620
> [    5.181893]  fib_magic.isra.0+0x110/0x11c
> [    5.185891]  fib_add_ifaddr+0xb8/0x190
> [    5.189629]  fib_inetaddr_event+0x8c/0x140
> 
> fib_treeref needs to be set after kzalloc. The old code had a ++ which
> led to the confusion when the int was replaced by a refcount_t.

Thank you for the patch!

My CI was also complaining of not being able to run kernel selftests [1].
Your patch fixes the issue, thanks!

Tested-by: Matthieu Baerts <matthieu.baerts@tessares.net>

Cheers,
Matt

[1] https://cirrus-ci.com/task/5688032394215424
-- 
Tessares | Belgium | Hybrid Access Solutions
www.tessares.net

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH net-next] ipv4: Fix refcount warning for new fib_info
  2021-08-02 17:58 ` Matthieu Baerts
@ 2021-08-02 18:04   ` David Ahern
  2021-08-02 20:20     ` Jakub Kicinski
  2021-08-03  7:39     ` yajun.deng
  0 siblings, 2 replies; 5+ messages in thread
From: David Ahern @ 2021-08-02 18:04 UTC (permalink / raw)
  To: Matthieu Baerts, David Ahern
  Cc: ciorneiioana, Yajun Deng, netdev, davem, kuba

On 8/2/21 11:58 AM, Matthieu Baerts wrote:
> Hi David,
> 
> On 02/08/2021 18:02, David Ahern wrote:
>> Ioana reported a refcount warning when booting over NFS:
>>
>> [    5.042532] ------------[ cut here ]------------
>> [    5.047184] refcount_t: addition on 0; use-after-free.
>> [    5.052324] WARNING: CPU: 7 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0xa4/0x150
>> ...
>> [    5.167201] Call trace:
>> [    5.169635]  refcount_warn_saturate+0xa4/0x150
>> [    5.174067]  fib_create_info+0xc00/0xc90
>> [    5.177982]  fib_table_insert+0x8c/0x620
>> [    5.181893]  fib_magic.isra.0+0x110/0x11c
>> [    5.185891]  fib_add_ifaddr+0xb8/0x190
>> [    5.189629]  fib_inetaddr_event+0x8c/0x140
>>
>> fib_treeref needs to be set after kzalloc. The old code had a ++ which
>> led to the confusion when the int was replaced by a refcount_t.
> 
> Thank you for the patch!
> 
> My CI was also complaining of not being able to run kernel selftests [1].
> Your patch fixes the issue, thanks!
> 
> Tested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
> 

Given how easily it is to trigger the warning, I get the impression the
original was an untested patch.

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH net-next] ipv4: Fix refcount warning for new fib_info
  2021-08-02 18:04   ` David Ahern
@ 2021-08-02 20:20     ` Jakub Kicinski
  2021-08-03  7:39     ` yajun.deng
  1 sibling, 0 replies; 5+ messages in thread
From: Jakub Kicinski @ 2021-08-02 20:20 UTC (permalink / raw)
  To: David Ahern
  Cc: Matthieu Baerts, David Ahern, ciorneiioana, Yajun Deng, netdev, davem

On Mon, 2 Aug 2021 12:04:01 -0600 David Ahern wrote:
> On 8/2/21 11:58 AM, Matthieu Baerts wrote:
> > Hi David,
> > 
> > On 02/08/2021 18:02, David Ahern wrote:  
> >> Ioana reported a refcount warning when booting over NFS:
> >>
> >> [    5.042532] ------------[ cut here ]------------
> >> [    5.047184] refcount_t: addition on 0; use-after-free.
> >> [    5.052324] WARNING: CPU: 7 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0xa4/0x150
> >> ...
> >> [    5.167201] Call trace:
> >> [    5.169635]  refcount_warn_saturate+0xa4/0x150
> >> [    5.174067]  fib_create_info+0xc00/0xc90
> >> [    5.177982]  fib_table_insert+0x8c/0x620
> >> [    5.181893]  fib_magic.isra.0+0x110/0x11c
> >> [    5.185891]  fib_add_ifaddr+0xb8/0x190
> >> [    5.189629]  fib_inetaddr_event+0x8c/0x140
> >>
> >> fib_treeref needs to be set after kzalloc. The old code had a ++ which
> >> led to the confusion when the int was replaced by a refcount_t.  
> > 
> > Thank you for the patch!
> > 
> > My CI was also complaining of not being able to run kernel selftests [1].
> > Your patch fixes the issue, thanks!
> > 
> > Tested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
> >   
> 
> Given how easily it is to trigger the warning, I get the impression the
> original was an untested patch.

Yeah :( In hindsight any refcount patch which doesn't contain a
refcount_set() is suspicious. Thanks for the quick fix, applied!

^ permalink raw reply	[flat|nested] 5+ messages in thread

* Re: [PATCH net-next] ipv4: Fix refcount warning for new fib_info
  2021-08-02 18:04   ` David Ahern
  2021-08-02 20:20     ` Jakub Kicinski
@ 2021-08-03  7:39     ` yajun.deng
  1 sibling, 0 replies; 5+ messages in thread
From: yajun.deng @ 2021-08-03  7:39 UTC (permalink / raw)
  To: Jakub Kicinski, David Ahern
  Cc: Matthieu Baerts, David Ahern, ciorneiioana, netdev, davem

August 3, 2021 4:20 AM, "Jakub Kicinski" <kuba@kernel.org> wrote:

> On Mon, 2 Aug 2021 12:04:01 -0600 David Ahern wrote:
> 
>> On 8/2/21 11:58 AM, Matthieu Baerts wrote:
>> Hi David,
>> 
>> On 02/08/2021 18:02, David Ahern wrote:
>> Ioana reported a refcount warning when booting over NFS:
>> 
>> [ 5.042532] ------------[ cut here ]------------
>> [ 5.047184] refcount_t: addition on 0; use-after-free.
>> [ 5.052324] WARNING: CPU: 7 PID: 1 at lib/refcount.c:25 refcount_warn_saturate+0xa4/0x150
>> ...
>> [ 5.167201] Call trace:
>> [ 5.169635] refcount_warn_saturate+0xa4/0x150
>> [ 5.174067] fib_create_info+0xc00/0xc90
>> [ 5.177982] fib_table_insert+0x8c/0x620
>> [ 5.181893] fib_magic.isra.0+0x110/0x11c
>> [ 5.185891] fib_add_ifaddr+0xb8/0x190
>> [ 5.189629] fib_inetaddr_event+0x8c/0x140
>> 
>> fib_treeref needs to be set after kzalloc. The old code had a ++ which
>> led to the confusion when the int was replaced by a refcount_t.
>> 
>> Thank you for the patch!
>> 
>> My CI was also complaining of not being able to run kernel selftests [1].
>> Your patch fixes the issue, thanks!
>> 
>> Tested-by: Matthieu Baerts <matthieu.baerts@tessares.net>
>> 
>> Given how easily it is to trigger the warning, I get the impression the
>> original was an untested patch.
> 
> Yeah :( In hindsight any refcount patch which doesn't contain a
> refcount_set() is suspicious. Thanks for the quick fix, applied!

Sorry for that, there is another patch needed to apply for the same reason. I just submitted it.

^ permalink raw reply	[flat|nested] 5+ messages in thread

end of thread, other threads:[~2021-08-03  7:39 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-02 16:02 [PATCH net-next] ipv4: Fix refcount warning for new fib_info David Ahern
2021-08-02 17:58 ` Matthieu Baerts
2021-08-02 18:04   ` David Ahern
2021-08-02 20:20     ` Jakub Kicinski
2021-08-03  7:39     ` yajun.deng

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