netdev - Re: [PATCH] SCTP: fix race between sctp_bind_addr_free() and sctp_bind_addr

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Date:	Wed, 18 May 2011 09:32:07 -0400
From:	Vladislav Yasevich <vladislav.yasevich@...com>
To:	Jacek Luczak <difrost.kernel@...il.com>
CC:	Eric Dumazet <eric.dumazet@...il.com>,
	Wei Yongjun <yjwei@...fujitsu.com>, netdev@...r.kernel.org
Subject: Re: [PATCH] SCTP: fix race between sctp_bind_addr_free() and sctp_bind_addr_conflict()

On 05/18/2011 09:11 AM, Jacek Luczak wrote:
> 2011/5/18 Eric Dumazet <eric.dumazet@...il.com>:
>> Le mercredi 18 mai 2011 à 14:47 +0200, Jacek Luczak a écrit :
>>
>>> OK then, at the end what Eric suggested is IMO valid:
>>>
>>> diff --git a/net/sctp/bind_addr.c b/net/sctp/bind_addr.c
>>> index faf71d1..0025d90 100644
>>> --- a/net/sctp/bind_addr.c
>>> +++ b/net/sctp/bind_addr.c
>>> @@ -144,10 +144,9 @@ static void sctp_bind_addr_clean(struct sctp_bind_addr *bp)
>>>         struct list_head *pos, *temp;
>>>
>>>         /* Empty the bind address list. */
>>> -       list_for_each_safe(pos, temp, &bp->address_list) {
>>> -               addr = list_entry(pos, struct sctp_sockaddr_entry, list);
>>> -               list_del(pos);
>>> -               kfree(addr);
>>> +       list_for_each_entry(pos, &bp->address_list, list) {
>>
>> a 'safe' version is needed here, since we remove items in iterator.
> 
> Yep.
> 
> diff --git a/net/sctp/bind_addr.c b/net/sctp/bind_addr.c
> index faf71d1..6150ac5 100644
> --- a/net/sctp/bind_addr.c
> +++ b/net/sctp/bind_addr.c
> @@ -140,14 +140,12 @@ void sctp_bind_addr_init(struct sctp_bind_addr
> *bp, __u16 port)
>  /* Dispose of the address list. */
>  static void sctp_bind_addr_clean(struct sctp_bind_addr *bp)
>  {
> -       struct sctp_sockaddr_entry *addr;
> -       struct list_head *pos, *temp;
> +       struct sctp_sockaddr_entry *addr, *temp;
> 
>         /* Empty the bind address list. */
> -       list_for_each_safe(pos, temp, &bp->address_list) {
> -               addr = list_entry(pos, struct sctp_sockaddr_entry, list);
> -               list_del(pos);
> -               kfree(addr);
> +       list_for_each_entry_safe(addr, temp, &bp->address_list, list) {
> +               list_del_rcu(&addr->list);
> +               call_rcu(&addr->rcu, sctp_local_addr_free);
>                 SCTP_DBG_OBJCNT_DEC(addr);
>         }
>  }
> 
> Does it now look good?

Yes.  It should the fix the race.

-vlad

> 
> -Jacek
> 

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