From 654d573845f35017dc397840fa03610fef3d08b0 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Sun, 19 Nov 2017 19:31:04 +0800 Subject: [PATCH] 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: 761876c857cb ("tap: XDP support") Signed-off-by: Xin Long Signed-off-by: David S. Miller --- drivers/net/tun.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 6bb1e604aadd..5a2ea78a008f 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -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; } -- 2.30.2