netfilter: nfnetlink_queue: hold nfnl mutex in event notifier

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We must serialize the release notifier and the config netlink function.
A concurrent thread can issue close() which can call the release function
while unrelated socket processes UNBIND request for same portid:

Oops: general protection fault, [..]
RIP: 0010:__instance_destroy+0x60/0x210 [nfnetlink_queue]
Call Trace:
 nfqnl_recv_config+0x9b0/0xdc0 [nfnetlink_queue]
 nfnetlink_rcv_msg+0x7c2/0xeb0
 ? __pfx_nfnetlink_rcv_msg+0x10/0x10

After this, parallel UNBIND and URELEASE events are impossible.

This change isn't nice, but its the shortest fix given instances
are not refcounted and the nfnetlink config callback drops the
rcu read lock early due to need for sleeping allocations.

Fixes: 7af4cc3fa1 ("[NETFILTER]: Add "nfnetlink_queue" netfilter queue handler over nfnetlink")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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Florian Westphal 2026-09-03 02:41:46 +02:00 • committed by Pablo Neira Ayuso

parent d644b23afe

commit 9461613afc

1 changed files with 5 additions and 3 deletions

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net/netfilter/nfnetlink_queue.c

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