From 6e8cfd6d9d8049e2fd5b2de8a328519dc58ea1e6 Mon Sep 17 00:00:00 2001 From: Toshiaki Makita Date: Fri, 13 Jul 2018 13:24:38 +0900 Subject: [PATCH] tun: Fix use-after-free on XDP_TX On XDP_TX we need to free up the frame only when tun_xdp_tx() returns a negative value. A positive value indicates that the packet is successfully enqueued to the ptr_ring, so freeing the page causes use-after-free. Fixes: 735fc4054b3a ("xdp: change ndo_xdp_xmit API to support bulking") Signed-off-by: Toshiaki Makita Acked-by: Jason Wang Acked-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- drivers/net/tun.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index a192a017cc68..f5727baac84a 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1688,7 +1688,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, case XDP_TX: get_page(alloc_frag->page); alloc_frag->offset += buflen; - if (tun_xdp_tx(tun->dev, &xdp)) + if (tun_xdp_tx(tun->dev, &xdp) < 0) goto err_redirect; rcu_read_unlock(); local_bh_enable(); -- 2.34.1