[PATCH net] netfilter: nfnetlink_queue: fix entry leak in bridge verdict error path

[Hyunwoo Kim <imv4bel@gmail.com>]

nfqnl_recv_verdict() calls find_dequeue_entry() to remove the queue
entry from the queue data structures, taking ownership of the entry.
For PF_BRIDGE packets, it then calls nfqa_parse_bridge() to parse VLAN
attributes.  If nfqa_parse_bridge() returns an error (e.g. NFQA_VLAN
present but NFQA_VLAN_TCI missing), the function returns immediately
without freeing the dequeued entry or its sk_buff.

This leaks the nf_queue_entry, its associated sk_buff, and all held
references (net_device refcounts, struct net refcount).  Repeated
triggering exhausts kernel memory.

Fix this by dropping the entry via nfqnl_reinject() with NF_DROP verdict
on the error path, consistent with other error handling in this file.

Fixes: 8d45ff22f1b4 ("netfilter: bridge: nf queue verdict to use NFQA_VLAN and NFQA_L2HDR")
Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
---
 net/netfilter/nfnetlink_queue.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 7f5248b5f1ee..47f7f62906e2 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -1546,8 +1546,10 @@ static int nfqnl_recv_verdict(struct sk_buff *skb, const struct nfnl_info *info,
 
 	if (entry->state.pf == PF_BRIDGE) {
 		err = nfqa_parse_bridge(entry, nfqa);
-		if (err < 0)
+		if (err < 0) {
+			nfqnl_reinject(entry, NF_DROP);
 			return err;
+		}
 	}
 
 	if (nfqa[NFQA_PAYLOAD]) {
-- 
2.43.0