[PATCH 5.13 514/800] skmsg: Clear skb redirect pointer before dropping it

[Greg Kroah-Hartman]

From: Cong Wang <cong.wang@xxxxxxxxxxxxx>

[ Upstream commit 30b9c54a707db4155735cf71f4600241c1b7b6ff ]

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@xxxxxxxxxxxxx>
Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
Acked-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20210615021342.7416-5-xiyou.wangcong@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/core/skmsg.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 43ce17a6a585..df545748cd6a 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -866,12 +866,14 @@ 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;
 	}
-- 
2.30.2