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Subject[PATCH 4.19 02/57] netfilter: clear skb->next in NF_HOOK_LIST()
Date

From: Cong Wang <cong.wang@bytedance.com>

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>

---
include/linux/netfilter.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -300,7 +300,7 @@ NF_HOOK_LIST(uint8_t pf, unsigned int ho

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);
}

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