Commit 30b9c54a authored by Cong Wang's avatar Cong Wang Committed by Daniel Borkmann
Browse files

skmsg: Clear skb redirect pointer before dropping it 



When we drop skb inside sk_psock_skb_redirect(), we have to clear
its skb->_sk_redir pointer too, otherwise kfree_skb() would
misinterpret it as a valid skb->_skb_refdst and dst_release()
would eventually complain.

Fixes: e3526bb9 ("skmsg: Move sk_redir from TCP_SKB_CB to skb")
Reported-by: default avatarJiang Wang <jiang.wang@bytedance.com>
Signed-off-by: default avatarCong Wang <cong.wang@bytedance.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Acked-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210615021342.7416-5-xiyou.wangcong@gmail.com
parent e00a5c33

net/core/skmsg.c

+2 −0
Original line number Diff line number Diff line
@@ -843,12 +843,14 @@ static void sk_psock_skb_redirect(struct sk_buff *skb) 
	 * a socket that is in this state so we drop the skb.

	 */

	if (!psock_other || sock_flag(sk_other, SOCK_DEAD)) {

		skb_bpf_redirect_clear(skb);

		kfree_skb(skb);

		return;

	}

	spin_lock_bh(&psock_other->ingress_lock);

	if (!sk_psock_test_state(psock_other, SK_PSOCK_TX_ENABLED)) {

		spin_unlock_bh(&psock_other->ingress_lock);

		skb_bpf_redirect_clear(skb);

		kfree_skb(skb);

		return;

	}