Commit 010d3c39 authored by Veaceslav Falico's avatar Veaceslav Falico Committed by David S. Miller
Browse files

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: default avatarDing Tianhong <>
Fixes: aeea64ac

 ("bonding: don't trust arp requests unless active slave really works")
CC: Jay Vosburgh <>
CC: Andy Gospodarek <>
Signed-off-by: default avatarVeaceslav Falico <>
Acked-by: default avatarDing Tianhong <>
Signed-off-by: default avatarDavid S. Miller <>
parent a1eabb01
......@@ -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),
else if (curr_active_slave &&
time_after(slave_last_rx(bond, curr_active_slave),
bond_validate_arp(bond, slave, tip, sip);
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