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tun: relax check on eth_get_headlen() return value 

syzkaller hit the WARN() in tun_get_user(), providing skb
with payload in fragments only, and nothing in skb->head

GRO layer is fine with this, so relax the check.

Fixes: 90e33d4594 ("tun: enable napi_gro_frags() for TUN/TAP driver")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-10-17 10:07:44 -07:00 committed by David S. Miller
parent 22ce97fe49
commit 010f245b9d
1 changed files with 1 additions and 1 deletions
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2
drivers/net/tun.c
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@ -1737,7 +1737,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
/* Exercise flow dissector code path. */
u32 headlen = eth_get_headlen(skb->data, skb_headlen(skb));
if (headlen > skb_headlen(skb) || headlen < ETH_HLEN) {
if (unlikely(headlen > skb_headlen(skb))) {
this_cpu_inc(tun->pcpu_stats->rx_dropped);
napi_free_frags(&tfile->napi);
mutex_unlock(&tfile->napi_mutex);