From: Florian Westphal fw@strlen.de
commit 3b836da4081fa585cf6c392f62557496f2cb0efe upstream.
In case someone combines bpf socket assign and nf_queue, then we will queue an skb who references a struct sock that did not have its reference count incremented.
As we leave rcu protection, there is no guarantee that skb->sk is still valid.
For refcount-less skb->sk case, try to increment the reference count and then override the destructor.
In case of failure we have two choices: orphan the skb and 'delete' preselect or let nf_queue() drop the packet.
Do the latter, it should not happen during normal operation.
Fixes: cf7fbe660f2d ("bpf: Add socket assign support") Acked-by: Joe Stringer joe@cilium.io Signed-off-by: Florian Westphal fw@strlen.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netfilter/nf_queue.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
--- a/net/netfilter/nf_queue.c +++ b/net/netfilter/nf_queue.c @@ -180,6 +180,18 @@ static int __nf_queue(struct sk_buff *sk break; }
+ if (skb_sk_is_prefetched(skb)) { + struct sock *sk = skb->sk; + + if (!sk_is_refcounted(sk)) { + if (!refcount_inc_not_zero(&sk->sk_refcnt)) + return -ENOTCONN; + + /* drop refcount on skb_orphan */ + skb->destructor = sock_edemux; + } + } + entry = kmalloc(sizeof(*entry) + route_key_size, GFP_ATOMIC); if (!entry) return -ENOMEM;