From: Nikolay Aleksandrov <nikolay(a)cumulusnetworks.com>
mainline inclusion
from mainline-v5.6-rc4
commit 823d81b0fa2cd83a640734e74caee338b5d3c093
category: bugfix
bugzilla: 185773
CVE: NA
-------------------------------------------------
In br_dev_xmit() we perform vlan filtering in br_allowed_ingress() but
if the packet has the vlan header inside (e.g. bridge with disabled
tx-vlan-offload) then the vlan filtering code will use skb_vlan_untag()
to extract the vid before filtering which in turn calls pskb_may_pull()
and we may end up with a stale eth pointer. Moreover the cached eth header
pointer will generally be wrong after that operation. Remove the eth header
caching and just use eth_hdr() directly, the compiler does the right thing
and calculates it only once so we don't lose anything.
Fixes: 057658cb33fb ("bridge: suppress arp pkts on BR_NEIGH_SUPPRESS ports")
Signed-off-by: Nikolay Aleksandrov <nikolay(a)cumulusnetworks.com>
Signed-off-by: David S. Miller <davem(a)davemloft.net>
Signed-off-by: Huang Guobin <huangguobin4(a)huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1(a)huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang(a)huawei.com>
---
net/bridge/br_device.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index a350c05b7ff5e..7b7784bb1cb99 100644
--- a/net/bridge/br_device.c
+++ b/net/bridge/br_device.c
@@ -39,7 +39,6 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
const struct nf_br_ops *nf_ops;
const unsigned char *dest;
- struct ethhdr *eth;
u16 vid = 0;
rcu_read_lock();
@@ -58,15 +57,14 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
BR_INPUT_SKB_CB(skb)->brdev = dev;
skb_reset_mac_header(skb);
- eth = eth_hdr(skb);
skb_pull(skb, ETH_HLEN);
if (!br_allowed_ingress(br, br_vlan_group_rcu(br), skb, &vid))
goto out;
if (IS_ENABLED(CONFIG_INET) &&
- (eth->h_proto == htons(ETH_P_ARP) ||
- eth->h_proto == htons(ETH_P_RARP)) &&
+ (eth_hdr(skb)->h_proto == htons(ETH_P_ARP) ||
+ eth_hdr(skb)->h_proto == htons(ETH_P_RARP)) &&
br->neigh_suppress_enabled) {
br_do_proxy_suppress_arp(skb, br, vid, NULL);
} else if (IS_ENABLED(CONFIG_IPV6) &&
--
2.25.1