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tun: fix rcu_read_lock imbalance in tun_build_skb

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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: 761876c857 ("tap: XDP support")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long
2017-11-19 19:31:04 +08:00
committed by David S. Miller
parent ed66dfaf23
commit 654d573845
1 changed files with 2 additions and 1 deletions
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3
drivers/net/tun.c
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@@ -1485,6 +1485,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
err = xdp_do_redirect(tun->dev, &xdp, xdp_prog); err = xdp_do_redirect(tun->dev, &xdp, xdp_prog);
if (err) if (err)
goto err_redirect; goto err_redirect;
rcu_read_unlock();
return NULL; return NULL;
case XDP_TX: case XDP_TX:
xdp_xmit = true; xdp_xmit = true;
@@ -1517,7 +1518,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
if (xdp_xmit) { if (xdp_xmit) {
skb->dev = tun->dev; skb->dev = tun->dev;
generic_xdp_tx(skb, xdp_prog); generic_xdp_tx(skb, xdp_prog);
rcu_read_lock(); rcu_read_unlock();
return NULL; return NULL;
} }