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bonding: fix bond_arp_rcv() race of curr_active_slave 

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>
Acked-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Veaceslav Falico 2014-02-20 12:07:57 +01:00 committed by David S. Miller
parent a1eabb0178
commit 010d3c3989
1 changed files with 7 additions and 3 deletions
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10
drivers/net/bonding/bond_main.c
View File

@ -2254,6 +2254,7 @@ int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond,
struct slave *slave) struct slave *slave)
{ {
struct arphdr *arp = (struct arphdr *)skb->data; struct arphdr *arp = (struct arphdr *)skb->data;
struct slave *curr_active_slave;
unsigned char *arp_ptr; unsigned char *arp_ptr;
__be32 sip, tip; __be32 sip, tip;
int alen, is_arp = skb->protocol == __cpu_to_be16(ETH_P_ARP); 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), bond->params.arp_validate, slave_do_arp_validate(bond, slave),
&sip, &tip); &sip, &tip);
curr_active_slave = rcu_dereference(bond->curr_active_slave);
/* /*
* Backup slaves won't see the ARP reply, but do come through * 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 * 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 * is done to avoid endless looping when we can't reach the
* arp_ip_target and fool ourselves with our own arp requests. * arp_ip_target and fool ourselves with our own arp requests.
*/ */
if (bond_is_active_slave(slave)) if (bond_is_active_slave(slave))
bond_validate_arp(bond, slave, sip, tip); bond_validate_arp(bond, slave, sip, tip);
else if (bond->curr_active_slave && else if (curr_active_slave &&
time_after(slave_last_rx(bond, bond->curr_active_slave), time_after(slave_last_rx(bond, curr_active_slave),
bond->curr_active_slave->last_link_up)) curr_active_slave->last_link_up))
bond_validate_arp(bond, slave, tip, sip); bond_validate_arp(bond, slave, tip, sip);
out_unlock: out_unlock: