[PATCH nf] netfilter: nf_queue: don't assume sk is full socket

[Florian Westphal <fw@strlen.de>]

There is no guarantee that state->sk refers to a full socket.

If refcount transitions to 0, sock_put calls sk_free which then ends up
with garbage fields.

I'd like to thank Oleksandr Natalenko and Jiri Benc for considerable
debug work and pointing out state->sk oddities.

Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 No reproducer, so there is a chance that the reported crash is caused by
 something else. That said, I don't see how sock_put use is safe here.

 net/netfilter/nf_queue.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index 6d12afabfe8a..178742a110d9 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -54,7 +54,7 @@ static void nf_queue_entry_release_refs(struct nf_queue_entry *entry)
 	dev_put(state->in);
 	dev_put(state->out);
 	if (state->sk)
-		sock_put(state->sk);
+		sock_gen_put(state->sk);
 
 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 	dev_put(entry->physin);
-- 
2.34.1