From: Veaceslav Falico <vfalico@xxxxxxxxxx>
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 <dingtianhong@xxxxxxxxxx>
Fixes: aeea64a ("bonding: don't trust arp requests unless active slave really works")
CC: Jay Vosburgh <fubar@xxxxxxxxxx>
CC: Andy Gospodarek <andy@xxxxxxxxxxxxx>
Signed-off-by: Veaceslav Falico <vfalico@xxxxxxxxxx>
Acked-by: Ding Tianhong <dingtianhong@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
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
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