From: Cong Wang <cong.wang@bytedance.com> stable inclusion from linux-4.19.161 commit 5460d62d661c0fc53bfe83493821b1dc3dc969f4 -------------------------------- NF_HOOK_LIST() uses list_del() to remove skb from the linked list, however, it is not sufficient as skb->next still points to other skb. We should just call skb_list_del_init() to clear skb->next, like the rest places which using skb list. This has been fixed in upstream by commit ca58fbe06c54 ("netfilter: add and use nf_hook_slow_list()"). Fixes: 9f17dbf04ddf ("netfilter: fix use-after-free in NF_HOOK_LIST") Reported-by: liuzx@knownsec.com Tested-by: liuzx@knownsec.com Cc: Florian Westphal <fw@strlen.de> Cc: Edward Cree <ecree@solarflare.com> Cc: stable@vger.kernel.org # between 4.19 and 5.4 Signed-off-by: Cong Wang <cong.wang@bytedance.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- include/linux/netfilter.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h index 72cb19c3db6a..9460a5635c90 100644 --- a/include/linux/netfilter.h +++ b/include/linux/netfilter.h @@ -300,7 +300,7 @@ NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk, INIT_LIST_HEAD(&sublist); list_for_each_entry_safe(skb, next, head, list) { - list_del(&skb->list); + skb_list_del_init(skb); if (nf_hook(pf, hook, net, sk, skb, in, out, okfn) == 1) list_add_tail(&skb->list, &sublist); } -- 2.25.1