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

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Date:	Wed, 18 May 2011 15:11:47 +0200
From:	Jacek Luczak <difrost.kernel@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Vladislav Yasevich <vladislav.yasevich@...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 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?

-Jacek
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