From: Veaceslav Falico <[email protected]> 3.12-stable review patch. If anyone has any objections, please let me know.
=============== commit 010d3c3989706d800ae72253773fa6537cc9f74c upstream. 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 <[email protected]> Fixes: aeea64a ("bonding: don't trust arp requests unless active slave really works") CC: Jay Vosburgh <[email protected]> CC: Andy Gospodarek <[email protected]> Signed-off-by: Veaceslav Falico <[email protected]> Acked-by: Ding Tianhong <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Jiri Slaby <[email protected]> --- 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 b3892b0d2e61..282d416559dc 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -2435,6 +2435,7 @@ 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; @@ -2479,6 +2480,8 @@ 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 @@ -2492,11 +2495,12 @@ 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->jiffies)) + else if (curr_active_slave && + time_after(slave_last_rx(bond, curr_active_slave), + curr_active_slave->jiffies)) bond_validate_arp(bond, slave, tip, sip); out_unlock: -- 2.7.2
