Commit 010f245b authored Oct 17, 2017 by Eric Dumazet Committed by David S. Miller Oct 19, 2017

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: 90e33d45 ("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>

parent 22ce97fe

drivers/net/tun.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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);