[PATCH 6.0 093/157] netfilter: conntrack: fix using __this_cpu_add in preemptible

Greg Kroah-Hartman
2022-12-12T13:44:20Z

From: Xin Long <lucien.xin@gmail.com>

[ Upstream commit 9464d0b68f11a9bc768370c3260ec02b3550447b ]

Currently in nf_conntrack_hash_check_insert(), when it fails in
nf_ct_ext_valid_pre/post(), NF_CT_STAT_INC() will be called in the
preemptible context, a call trace can be triggered:

BUG: using __this_cpu_add() in preemptible [00000000] code: conntrack/1636
caller is nf_conntrack_hash_check_insert+0x45/0x430 [nf_conntrack]
Call Trace:
<TASK>
dump_stack_lvl+0x33/0x46
check_preemption_disabled+0xc3/0xf0
nf_conntrack_hash_check_insert+0x45/0x430 [nf_conntrack]
ctnetlink_create_conntrack+0x3cd/0x4e0 [nf_conntrack_netlink]
ctnetlink_new_conntrack+0x1c0/0x450 [nf_conntrack_netlink]
nfnetlink_rcv_msg+0x277/0x2f0 [nfnetlink]
netlink_rcv_skb+0x50/0x100
nfnetlink_rcv+0x65/0x144 [nfnetlink]
netlink_unicast+0x1ae/0x290
netlink_sendmsg+0x257/0x4f0
sock_sendmsg+0x5f/0x70

This patch is to fix it by changing to use NF_CT_STAT_INC_ATOMIC() for
nf_ct_ext_valid_pre/post() check in nf_conntrack_hash_check_insert(),
as well as nf_ct_ext_valid_post() in __nf_conntrack_confirm().

Note that nf_ct_ext_valid_pre() check in __nf_conntrack_confirm() is
safe to use NF_CT_STAT_INC(), as it's under local_bh_disable().

Fixes: c56716c69ce1 ("netfilter: extensions: introduce extension genid count")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netfilter/nf_conntrack_core.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 60289c074eef..df46e9a35e47 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -891,7 +891,7 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct)
zone = nf_ct_zone(ct);

if (!nf_ct_ext_valid_pre(ct->ext)) {
- NF_CT_STAT_INC(net, insert_failed);
+ NF_CT_STAT_INC_ATOMIC(net, insert_failed);
return -ETIMEDOUT;
}

@@ -938,7 +938,7 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct)

if (!nf_ct_ext_valid_post(ct->ext)) {
nf_ct_kill(ct);
- NF_CT_STAT_INC(net, drop);
+ NF_CT_STAT_INC_ATOMIC(net, drop);
return -ETIMEDOUT;
}

@@ -1275,7 +1275,7 @@ __nf_conntrack_confirm(struct sk_buff *skb)
*/
if (!nf_ct_ext_valid_post(ct->ext)) {
nf_ct_kill(ct);
- NF_CT_STAT_INC(net, drop);
+ NF_CT_STAT_INC_ATOMIC(net, drop);
return NF_DROP;
}

--
2.35.1