From: Willem de Bruijn <[email protected]>
Tun in IFF_NAPI_FRAGS mode calls napi_gro_frags. Unlike netif_rx and
netif_gro_receive, this expects skb->data to point to the mac layer.
But skb_probe_transport_header, __skb_get_hash_symmetric, and
xdp_do_generic in tun_get_user need skb->data to point to the network
header. Flow dissection also needs skb->protocol set, so
eth_type_trans has to be called.
Temporarily pull ETH_HLEN to make control flow the same for frags and
not frags. Then push the header just before calling napi_gro_frags.
Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver")
Signed-off-by: Willem de Bruijn <[email protected]>
---
drivers/net/tun.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 44889eba1dbc..b984733c6c31 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1871,8 +1871,11 @@ static ssize_t tun_get_user(struct tun_struct *tun,
struct tun_file *tfile,
skb->dev = tun->dev;
break;
case IFF_TAP:
- if (!frags)
- skb->protocol = eth_type_trans(skb, tun->dev);
+ if (frags && !pskb_may_pull(skb, ETH_HLEN)) {
+ err = -ENOMEM;
+ goto drop;
+ }
+ skb->protocol = eth_type_trans(skb, tun->dev);
break;
}
@@ -1929,9 +1932,12 @@ static ssize_t tun_get_user(struct tun_struct *tun,
struct tun_file *tfile,
}
if (frags) {
+ u32 headlen;
+
/* Exercise flow dissector code path. */
- u32 headlen = eth_get_headlen(tun->dev, skb->data,
- skb_headlen(skb));
+ skb_push(skb, ETH_HLEN);
+ headlen = eth_get_headlen(tun->dev, skb->data,
+ skb_headlen(skb));
if (unlikely(headlen > skb_headlen(skb))) {
this_cpu_inc(tun->pcpu_stats->rx_dropped);
--
2.27.0.rc0.183.gde8f92d652-goog
