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 <fw@xxxxxxxxx>
---
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 @@ void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict)
kfree_skb(skb);
}
- kfree(entry);
+ nf_queue_entry_free(entry);
}
EXPORT_SYMBOL(nf_reinject);
--
2.24.1
