net/llc: avoid BUG_ON() in skb_orphan()
It seems nobody used LLC since linux-3.12.
Fortunately fuzzers like syzkaller still know how to run this code,
otherwise it would be no fun.
Setting skb->sk without skb->destructor leads to all kinds of
bugs, we now prefer to be very strict about it.
Ideally here we would use skb_set_owner() but this helper does not exist yet,
only CAN seems to have a private helper for that.
Fixes: 376c7311bdb6 ("net: add a temporary sanity check in skb_orphan()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/llc/llc_conn.c b/net/llc/llc_conn.c
index 3e821da..8bc5a1b 100644
--- a/net/llc/llc_conn.c
+++ b/net/llc/llc_conn.c
@@ -821,7 +821,10 @@ void llc_conn_handler(struct llc_sap *sap, struct sk_buff *skb)
* another trick required to cope with how the PROCOM state
* machine works. -acme
*/
+ skb_orphan(skb);
+ sock_hold(sk);
skb->sk = sk;
+ skb->destructor = sock_efree;
}
if (!sock_owned_by_user(sk))
llc_conn_rcv(sk, skb);
