[PATCH AUTOSEL 4.19 143/158] bonding: validate ip header before check IPPROTO_IGMP

Sasha Levin
2019-07-15T14:27:29Z

From: Cong Wang <xiyou.wangcong@gmail.com>

[ Upstream commit 9d1bc24b52fb8c5d859f9a47084bf1179470e04c ]

bond_xmit_roundrobin() checks for IGMP packets but it parses
the IP header even before checking skb->protocol.

We should validate the IP header with pskb_may_pull() before
using iph->protocol.

Reported-and-tested-by: syzbot+e5be16aa39ad6e755391@syzkaller.appspotmail.com
Fixes: a2fd940f4cff ("bonding: fix broken multicast with round-robin mode")
Cc: Jay Vosburgh <j.vosburgh@gmail.com>
Cc: Veaceslav Falico <vfalico@gmail.com>
Cc: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/bonding/bond_main.c | 37 ++++++++++++++++++++-------------
1 file changed, 23 insertions(+), 14 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 7e162fff01ab..be0b785becd0 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -3852,8 +3852,8 @@ static netdev_tx_t bond_xmit_roundrobin(struct sk_buff *skb,
struct net_device *bond_dev)
{
struct bonding *bond = netdev_priv(bond_dev);
- struct iphdr *iph = ip_hdr(skb);
struct slave *slave;
+ int slave_cnt;
u32 slave_id;

/* Start with the curr_active_slave that joined the bond as the
@@ -3862,23 +3862,32 @@ static netdev_tx_t bond_xmit_roundrobin(struct sk_buff *skb,
* send the join/membership reports. The curr_active_slave found
* will send all of this type of traffic.
*/
- if (iph->protocol == IPPROTO_IGMP && skb->protocol == htons(ETH_P_IP)) {
- slave = rcu_dereference(bond->curr_active_slave);
- if (slave)
- bond_dev_queue_xmit(bond, skb, slave->dev);
- else
- bond_xmit_slave_id(bond, skb, 0);
- } else {
- int slave_cnt = READ_ONCE(bond->slave_cnt);
+ if (skb->protocol == htons(ETH_P_IP)) {
+ int noff = skb_network_offset(skb);
+ struct iphdr *iph;

- if (likely(slave_cnt)) {
- slave_id = bond_rr_gen_slave_id(bond);
- bond_xmit_slave_id(bond, skb, slave_id % slave_cnt);
- } else {
- bond_tx_drop(bond_dev, skb);
+ if (unlikely(!pskb_may_pull(skb, noff + sizeof(*iph))))
+ goto non_igmp;
+
+ iph = ip_hdr(skb);
+ if (iph->protocol == IPPROTO_IGMP) {
+ slave = rcu_dereference(bond->curr_active_slave);
+ if (slave)
+ bond_dev_queue_xmit(bond, skb, slave->dev);
+ else
+ bond_xmit_slave_id(bond, skb, 0);
+ return NETDEV_TX_OK;
}
}

+non_igmp:
+ slave_cnt = READ_ONCE(bond->slave_cnt);
+ if (likely(slave_cnt)) {
+ slave_id = bond_rr_gen_slave_id(bond);
+ bond_xmit_slave_id(bond, skb, slave_id % slave_cnt);
+ } else {
+ bond_tx_drop(bond_dev, skb);
+ }
return NETDEV_TX_OK;
}

--
2.20.1