[PATCH net-next 3/3] net/sched: act_ct: fix clobber qdisc_skb_cb in defrag

[wenxu@ucloud.cn]

From: wenxu <wenxu@ucloud.cn>

using nf_ct_frag_gather to defrag in act_ct to elide CB clear.
Avoid serious crashes and problems in ct subsystem. Because Some packet
schedulers store pointers in the qdisc CB private area and Parallel
accesses to the SKB.

Fixes: b57dc7c13ea9 ("net/sched: Introduce action ct")
Signed-off-by: wenxu <wenxu@ucloud.cn>
---
 net/sched/act_ct.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index 20f3d11..75562f4 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -31,6 +31,7 @@
 #include <net/netfilter/nf_conntrack_zones.h>
 #include <net/netfilter/nf_conntrack_helper.h>
 #include <net/netfilter/nf_conntrack_acct.h>
+#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
 #include <uapi/linux/netfilter/nf_nat.h>
 
@@ -695,14 +696,18 @@ static int tcf_ct_handle_fragments(struct net *net, struct sk_buff *skb,
 	skb_get(skb);
 
 	if (family == NFPROTO_IPV4) {
+#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV4)
 		enum ip_defrag_users user = IP_DEFRAG_CONNTRACK_IN + zone;
 
-		memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
 		local_bh_disable();
-		err = ip_defrag(net, skb, user);
+		err = nf_ct_frag_gather(net, skb, user, NULL);
 		local_bh_enable();
 		if (err && err != -EINPROGRESS)
 			goto out_free;
+#else
+		err = -EOPNOTSUPP;
+		goto out_free;
+#endif
 	} else { /* NFPROTO_IPV6 */
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
 		enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone;
-- 
1.8.3.1