[PATCH] vxlan: fix a use after free in vxlan_encap_bypass

[r***@gmail.com]

From: Li RongQing <***@gmail.com>

when netif_rx() is done, the netif_rx handled skb maybe be freed,
and should not be used.

Signed-off-by: Li RongQing <***@gmail.com>
---
drivers/net/vxlan.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 6f83be7..f677cd0 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1668,6 +1668,8 @@ static void vxlan_encap_bypass(struct sk_buff *skb, struct vxlan_dev *src_vxlan,
struct pcpu_sw_netstats *tx_stats, *rx_stats;
union vxlan_addr loopback;
union vxlan_addr *remote_ip = &dst_vxlan->default_dst.remote_ip;
+ struct net_device *dev = skb->dev;
+ int len = skb->len;

tx_stats = this_cpu_ptr(src_vxlan->dev->tstats);
rx_stats = this_cpu_ptr(dst_vxlan->dev->tstats);
@@ -1691,16 +1693,16 @@ static void vxlan_encap_bypass(struct sk_buff *skb, struct vxlan_dev *src_vxlan,

u64_stats_update_begin(&tx_stats->syncp);
tx_stats->tx_packets++;
- tx_stats->tx_bytes += skb->len;
+ tx_stats->tx_bytes += len;
u64_stats_update_end(&tx_stats->syncp);

if (netif_rx(skb) == NET_RX_SUCCESS) {
u64_stats_update_begin(&rx_stats->syncp);
rx_stats->rx_packets++;
- rx_stats->rx_bytes += skb->len;
+ rx_stats->rx_bytes += len;
u64_stats_update_end(&rx_stats->syncp);
} else {
- skb->dev->stats.rx_dropped++;
+ dev->stats.rx_dropped++;
}
}

[David Miller]

From: ***@gmail.com
Date: Thu, 16 Oct 2014 08:49:41 +0800

Post by r***@gmail.com
when netif_rx() is done, the netif_rx handled skb maybe be freed,
and should not be used.

Looks good, applied, and queued up for -stable thanks!