[PATCH] tuntap: reset network header before calling skb_get_rxhash()

[Eric Dumazet <eric.dumazet@gmail.com>]

From: Eric Dumazet <edumazet@google.com>

Commit 499744209b2c (tuntap: dont use skb after netif_rx_ni(skb))
introduced another bug.

skb_get_rxhash() needs to access the network header, and it was
set for us in netif_rx_ni().

We need to reset network header or else skb_flow_dissect() behavior
is out of control.

Reported-and-tested-by: Kirill A. Shutemov <kirill@shutemov.name>
Tested-by: Daniel Borkmann <daniel.borkmann@tik.ee.ethz.ch>
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 drivers/net/tun.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 255a9f5..173acf5 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1199,6 +1199,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 		skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
 	}
 
+	skb_reset_network_header(skb);
 	rxhash = skb_get_rxhash(skb);
 	netif_rx_ni(skb);