Previous commit 2d72afb34065 ("netfilter: nf_conntrack: fix crash due to
removal of uninitialised entry") move the IPS_CONFIRMED assignment after
the hash table insertion.
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:
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
---[ 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
issue. Fix it by rereading nfct from skb.
Fixes: 62e7151ae3eb ("netfilter: bridge: confirm multicast packets before passing them up the stack")
Signed-off-by: Wang Liang
---
net/bridge/br_netfilter_hooks.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 94cbe967d1c1..55b1b7dcb609 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -626,6 +626,7 @@ static unsigned int br_nf_local_in(void *priv,
break;
}
+ nfct = skb_nfct(skb);
ct = container_of(nfct, struct nf_conn, ct_general);
WARN_ON_ONCE(!nf_ct_is_confirmed(ct));
--
2.33.0