From af370ab36fcd19f04e3408c402608e7e56e6f188 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Fri, 27 Mar 2020 03:24:48 +0100 Subject: netfilter: nf_queue: do not release refcouts until nf_reinject is done nf_queue is problematic when another NF_QUEUE invocation happens from nf_reinject(). 1. nf_queue is invoked, increments state->sk refcount. 2. skb is queued, waiting for verdict. 3. sk is closed/released. 3. verdict comes back, nf_reinject is called. 4. nf_reinject drops the reference -- refcount can now drop to 0 Instead of get_ref/release_ref pattern, we need to nest the get_ref calls: get_ref get_ref release_ref release_ref So that when we invoke the next processing stage (another netfilter or the okfn()), we hold at least one reference count on the devices/socket. After previous patch, it is now safe to put the entry even after okfn() has potentially free'd the skb. Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_queue.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c index 96eb72908467..aadccdd117f0 100644 --- a/net/netfilter/nf_queue.c +++ b/net/netfilter/nf_queue.c @@ -303,12 +303,10 @@ void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict) hooks = nf_hook_entries_head(net, pf, entry->state.hook); - nf_queue_entry_release_refs(entry); - i = entry->hook_index; if (WARN_ON_ONCE(!hooks || i >= hooks->num_hook_entries)) { kfree_skb(skb); - kfree(entry); + nf_queue_entry_free(entry); return; } @@ -347,6 +345,6 @@ next_hook: kfree_skb(skb); } - kfree(entry); + nf_queue_entry_free(entry); } EXPORT_SYMBOL(nf_reinject); -- cgit v1.2.3