Commit 654d5738 authored Nov 19, 2017 by Xin Long Committed by David S. Miller Nov 19, 2017

tun: fix rcu_read_lock imbalance in tun_build_skb



rcu_read_lock in tun_build_skb is used to rcu_dereference tun->xdp_prog
safely, rcu_read_unlock should be done in every return path.

Now I could see one place missing it, where it returns NULL in switch-case
XDP_REDIRECT,  another palce using rcu_read_lock wrongly, where it returns
NULL in if (xdp_xmit) chunk.

So fix both in this patch.

Fixes: 761876c8 ("tap: XDP support")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent ed66dfaf

drivers/net/tun.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1485,6 +1485,7 @@ static struct sk_buff tun_build_skb(struct tun_struct tun,
		err = xdp_do_redirect(tun->dev, &xdp, xdp_prog);
		if (err)
		goto err_redirect;
		rcu_read_unlock();
		return NULL;
		case XDP_TX:
		xdp_xmit = true;
		@@ -1517,7 +1518,7 @@ static struct sk_buff tun_build_skb(struct tun_struct tun,
		if (xdp_xmit) {
		skb->dev = tun->dev;
		generic_xdp_tx(skb, xdp_prog);
		rcu_read_lock();
		rcu_read_unlock();
		return NULL;
		}