| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.10 045/105] netfilter: nf_queue: handle socket prefetch | Date | Mon, 7 Mar 2022 10:18:48 +0100 |
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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 @@ -189,6 +189,18 @@ 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;
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