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When send a broadcast packet to a tap device, which was added to a bridge,
br_nf_local_in() is called to confirm the conntrack. If another conntrack
with the same hash value is added to the hash table, which can be
triggered by a normal packet to a non-bridge device, the below warning
may happen.
------------[ cut here ]------------
WARNING: CPU: 1 PID: 96 at net/bridge/br_netfilter_hooks.c:632 br_nf_local_in+0x168/0x200
CPU: 1 UID: 0 PID: 96 Comm: tap_send Not tainted 6.17.0-rc2-dirty #44 PREEMPT(voluntary)
RIP: 0010:br_nf_local_in+0x168/0x200
Call Trace:
<TASK>
nf_hook_slow+0x3e/0xf0
br_pass_frame_up+0x103/0x180
br_handle_frame_finish+0x2de/0x5b0
br_nf_hook_thresh+0xc0/0x120
br_nf_pre_routing_finish+0x168/0x3a0
br_nf_pre_routing+0x237/0x5e0
br_handle_frame+0x1ec/0x3c0
__netif_receive_skb_core+0x225/0x1210
__netif_receive_skb_one_core+0x37/0xa0
netif_receive_skb+0x36/0x160
tun_get_user+0xa54/0x10c0
tun_chr_write_iter+0x65/0xb0
vfs_write+0x305/0x410
ksys_write+0x60/0xd0
do_syscall_64+0xa4/0x260
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
---[ end trace 0000000000000000 ]---
To solve the hash conflict, nf_ct_resolve_clash() try to merge the
conntracks, and update skb->_nfct. However, br_nf_local_in() still use the
old ct from local variable 'nfct' after confirm(), which leads to this
warning.
If confirm() does not insert the conntrack entry and return NF_DROP, the
warning may also occur. There is no need to reserve the WARN_ON_ONCE, just
remove it.
Link: https://lore.kernel.org/netdev/20250820043329.2902014-1-wangliang74@huawei.com/
Fixes:
|
||
|---|---|---|
| .. | ||
| netfilter | ||
| br_arp_nd_proxy.c | ||
| br_cfm_netlink.c | ||
| br_cfm.c | ||
| br_device.c | ||
| br_fdb.c | ||
| br_forward.c | ||
| br_if.c | ||
| br_input.c | ||
| br_ioctl.c | ||
| br_mdb.c | ||
| br_mrp_netlink.c | ||
| br_mrp_switchdev.c | ||
| br_mrp.c | ||
| br_mst.c | ||
| br_multicast_eht.c | ||
| br_multicast.c | ||
| br_netfilter_hooks.c | ||
| br_netfilter_ipv6.c | ||
| br_netlink_tunnel.c | ||
| br_netlink.c | ||
| br_nf_core.c | ||
| br_private_cfm.h | ||
| br_private_mcast_eht.h | ||
| br_private_mrp.h | ||
| br_private_stp.h | ||
| br_private_tunnel.h | ||
| br_private.h | ||
| br_stp_bpdu.c | ||
| br_stp_if.c | ||
| br_stp_timer.c | ||
| br_stp.c | ||
| br_switchdev.c | ||
| br_sysfs_br.c | ||
| br_sysfs_if.c | ||
| br_vlan_options.c | ||
| br_vlan_tunnel.c | ||
| br_vlan.c | ||
| br.c | ||
| Kconfig | ||
| Makefile | ||