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

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Date:	Wed, 18 May 2011 14:50:46 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jacek Luczak <difrost.kernel@...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()

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.

> +               list_del_rcu(&pos->list);
> +               call_rcu(&pos->rcu, sctp_local_addr_free);
>                 SCTP_DBG_OBJCNT_DEC(addr);
>         }
>  }
> 
> 
> I will test this. Should be safe, avoid race not only in that case and
> it consistent.
> 
> -Jacek


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