* [PATCH 5.4 04/98] netfilter: clear skb->next in NF_HOOK_LIST()
[not found] <20201201084652.827177826@linuxfoundation.org>
@ 2020-12-01 8:52 ` Greg Kroah-Hartman
0 siblings, 0 replies; only message in thread
From: Greg Kroah-Hartman @ 2020-12-01 8:52 UTC (permalink / raw)
To: linux-kernel, netdev
Cc: Greg Kroah-Hartman, stable, liuzx, Florian Westphal, Edward Cree,
Cong Wang
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
@@ -316,7 +316,7 @@ 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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