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

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Message-ID: <BANLkTi=7T5-mGCWv_ge=HSGALVp4HpUsiA@mail.gmail.com>
Date:	Wed, 18 May 2011 15:39:14 +0200
From:	Jacek Luczak <difrost.kernel@...il.com>
To:	Vladislav Yasevich <vladislav.yasevich@...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()

2011/5/18 Vladislav Yasevich <vladislav.yasevich@...com>:
> 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.
>

Thanks guys then for your guidance. I will repost final patch.

-Jacek
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