[PATCH RESEND bpf v3 4/8] skmsg: clear skb redirect pointer before dropping it

[Cong Wang <xiyou.wangcong@gmail.com>]

From: Cong Wang <cong.wang@bytedance.com>

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: e3526bb92a20 ("skmsg: Move sk_redir from TCP_SKB_CB to skb")
Reported-by: Jiang Wang <jiang.wang@bytedance.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
---
 net/core/skmsg.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index f9a81b314e4c..4334720e2a04 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -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;
 	}
-- 
2.25.1