CVE-2023-53492 netfilter: nf_tables: do not ignore genmask when looking up chain by id
In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_tables: do not ignore genmask when looking up chain by id

When adding a rule to a chain referring to its ID, if that chain had been
deleted on the same batch, the rule might end up referring to a deleted
chain.

This will lead to a WARNING like following:

[   33.098431] ------------[ cut here ]------------
[   33.098678] WARNING: CPU: 5 PID: 69 at net/netfilter/nf_tables_api.c:2037 nf_tables_chain_destroy+0x23d/0x260
[   33.099217] Modules linked in:
[   33.099388] CPU: 5 PID: 69 Comm: kworker/5:1 Not tainted 6.4.0+ #409
[   33.099726] Workqueue: events nf_tables_trans_destroy_work
[   33.100018] RIP: 0010:nf_tables_chain_destroy+0x23d/0x260
[   33.100306] Code: 8b 7c 24 68 e8 64 9c ed fe 4c 89 e7 e8 5c 9c ed fe 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d 31 c0 89 c6 89 c7 c3 cc cc cc cc <0f> 0b 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d 31 c0 89 c6 89 c7
[   33.101271] RSP: 0018:ffffc900004ffc48 EFLAGS: 00010202
[   33.101546] RAX: 0000000000000001 RBX: ffff888006fc0a28 RCX: 0000000000000000
[   33.101920] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
[   33.102649] RBP: ffffc900004ffc78 R08: 0000000000000000 R09: 0000000000000000
[   33.103018] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880135ef500
[   33.103385] R13: 0000000000000000 R14: dead000000000122 R15: ffff888006fc0a10
[   33.103762] FS:  0000000000000000(0000) GS:ffff888024c80000(0000) knlGS:0000000000000000
[   33.104184] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   33.104493] CR2: 00007fe863b56a50 CR3: 00000000124b0001 CR4: 0000000000770ee0
[   33.104872] PKRU: 55555554
[   33.104999] Call Trace:
[   33.105113]  <TASK>
[   33.105214]  ? show_regs+0x72/0x90
[   33.105371]  ? __warn+0xa5/0x210
[   33.105520]  ? nf_tables_chain_destroy+0x23d/0x260
[   33.105732]  ? report_bug+0x1f2/0x200
[   33.105902]  ? handle_bug+0x46/0x90
[   33.106546]  ? exc_invalid_op+0x19/0x50
[   33.106762]  ? asm_exc_invalid_op+0x1b/0x20
[   33.106995]  ? nf_tables_chain_destroy+0x23d/0x260
[   33.107249]  ? nf_tables_chain_destroy+0x30/0x260
[   33.107506]  nf_tables_trans_destroy_work+0x669/0x680
[   33.107782]  ? mark_held_locks+0x28/0xa0
[   33.107996]  ? __pfx_nf_tables_trans_destroy_work+0x10/0x10
[   33.108294]  ? _raw_spin_unlock_irq+0x28/0x70
[   33.108538]  process_one_work+0x68c/0xb70
[   33.108755]  ? lock_acquire+0x17f/0x420
[   33.108977]  ? __pfx_process_one_work+0x10/0x10
[   33.109218]  ? do_raw_spin_lock+0x128/0x1d0
[   33.109435]  ? _raw_spin_lock_irq+0x71/0x80
[   33.109634]  worker_thread+0x2bd/0x700
[   33.109817]  ? __pfx_worker_thread+0x10/0x10
[   33.110254]  kthread+0x18b/0x1d0
[   33.110410]  ? __pfx_kthread+0x10/0x10
[   33.110581]  ret_from_fork+0x29/0x50
[   33.110757]  </TASK>
[   33.110866] irq event stamp: 1651
[   33.111017] hardirqs last  enabled at (1659): [<ffffffffa206a209>] __up_console_sem+0x79/0xa0
[   33.111379] hardirqs last disabled at (1666): [<ffffffffa206a1ee>] __up_console_sem+0x5e/0xa0
[   33.111740] softirqs last  enabled at (1616): [<ffffffffa1f5d40e>] __irq_exit_rcu+0x9e/0xe0
[   33.112094] softirqs last disabled at (1367): [<ffffffffa1f5d40e>] __irq_exit_rcu+0x9e/0xe0
[   33.112453] ---[ end trace 0000000000000000 ]---

This is due to the nft_chain_lookup_byid ignoring the genmask. After this
change, adding the new rule will fail as it will not find the chain.
Affected products: vendor: Linux
product: Linux
default_status: unaffected
vendor: Linux
product: Linux
default_status: affected
Published: 2025-10-01T11:45:44.019Z