Subject: [PATCH 2/5] netfilter: nft_socket: fix erroneous socket assignment

From: Pablo Neira Ayuso <[email-masked]>
Date: Wed, 4 Sep 2019 21:36:43 +0200

From: Fernando Fernandez Mancera <[email-masked]>

The socket assignment is wrong, see skb_orphan():
When skb->destructor callback is not set, but skb->sk is set, this hits BUG().

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1651813
Fixes: 554ced0a6e29 ("netfilter: nf_tables: add support for native socket matching")
Signed-off-by: Fernando Fernandez Mancera <[email-masked]>
Signed-off-by: Pablo Neira Ayuso <[email-masked]>
---
 net/netfilter/nft_socket.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nft_socket.c b/net/netfilter/nft_socket.c
index d7f3776dfd71..637ce3e8c575 100644
--- a/net/netfilter/nft_socket.c
+++ b/net/netfilter/nft_socket.c
@@ -47,9 +47,6 @@ static void nft_socket_eval(const struct nft_expr *expr,
 		return;
 	}
 
-	/* So that subsequent socket matching not to require other lookups. */
-	skb->sk = sk;
-
 	switch(priv->key) {
 	case NFT_SOCKET_TRANSPARENT:
 		nft_reg_store8(dest, inet_sk_transparent(sk));
@@ -66,6 +63,9 @@ static void nft_socket_eval(const struct nft_expr *expr,
 		WARN_ON(1);
 		regs->verdict.code = NFT_BREAK;
 	}
+
+	if (sk != skb->sk)
+		sock_gen_put(sk);
 }
 
 static const struct nla_policy nft_socket_policy[NFTA_SOCKET_MAX + 1] = {
-- 
2.11.0