From: Ding Tianhong <dingtianhong@huawei•com>
To: Veaceslav Falico <vfalico@redhat•com>, <netdev@vger•kernel.org>
Cc: Jay Vosburgh <fubar@us•ibm.com>, Andy Gospodarek <andy@greyhouse•net>
Subject: Re: [PATCH net] bonding: fix bond_arp_rcv() race of curr_active_slave
Date: Thu, 20 Feb 2014 19:49:28 +0800 [thread overview]
Message-ID: <5305EBC8.3070207@huawei.com> (raw)
In-Reply-To: <1392894477-5477-1-git-send-email-vfalico@redhat.com>
On 2014/2/20 19:07, Veaceslav Falico wrote:
> bond->curr_active_slave can be changed between its deferences, even to
> NULL, and thus we might panic.
>
> We're always holding the rcu (rx_handler->bond_handle_frame()->bond_arp_rcv())
> so fix this by rcu_dereferencing() it and using the saved.
>
> Reported-by: Ding Tianhong <dingtianhong@huawei•com>
> Fixes: aeea64a ("bonding: don't trust arp requests unless active slave really works")
> CC: Jay Vosburgh <fubar@us•ibm.com>
> CC: Andy Gospodarek <andy@greyhouse•net>
> Signed-off-by: Veaceslav Falico <vfalico@redhat•com>
> ---
> drivers/net/bonding/bond_main.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 71edf03..bd70bbc 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -2254,6 +2254,7 @@ int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond,
> struct slave *slave)
> {
> struct arphdr *arp = (struct arphdr *)skb->data;
> + struct slave *curr_active_slave;
> unsigned char *arp_ptr;
> __be32 sip, tip;
> int alen, is_arp = skb->protocol == __cpu_to_be16(ETH_P_ARP);
> @@ -2299,6 +2300,8 @@ int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond,
> bond->params.arp_validate, slave_do_arp_validate(bond, slave),
> &sip, &tip);
>
> + curr_active_slave = rcu_dereference(bond->curr_active_slave);
> +
> /*
> * Backup slaves won't see the ARP reply, but do come through
> * here for each ARP probe (so we swap the sip/tip to validate
> @@ -2312,11 +2315,12 @@ int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond,
> * is done to avoid endless looping when we can't reach the
> * arp_ip_target and fool ourselves with our own arp requests.
> */
> +
> if (bond_is_active_slave(slave))
> bond_validate_arp(bond, slave, sip, tip);
> - else if (bond->curr_active_slave &&
> - time_after(slave_last_rx(bond, bond->curr_active_slave),
> - bond->curr_active_slave->last_link_up))
> + else if (curr_active_slave &&
> + time_after(slave_last_rx(bond, curr_active_slave),
> + curr_active_slave->last_link_up))
> bond_validate_arp(bond, slave, tip, sip);
>
> out_unlock:
>
Acked-by: Ding Tianhong <dingtianhong@huawei•com>
prev parent reply other threads:[~2014-02-20 11:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-20 11:07 [PATCH net] bonding: fix bond_arp_rcv() race of curr_active_slave Veaceslav Falico
2014-02-20 11:15 ` Veaceslav Falico
2014-02-20 18:21 ` David Miller
2014-02-20 11:49 ` Ding Tianhong [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5305EBC8.3070207@huawei.com \
--to=dingtianhong@huawei$(echo .)com \
--cc=andy@greyhouse$(echo .)net \
--cc=fubar@us$(echo .)ibm.com \
--cc=netdev@vger$(echo .)kernel.org \
--cc=vfalico@redhat$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox