From: Florian Westphal Date: Thu, 19 May 2022 22:02:04 +0000 (+0200) Subject: netfilter: conntrack: re-fetch conntrack after insertion X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=56b14ecec97f39118bf85c9ac2438c5a949509ed;p=linux.git netfilter: conntrack: re-fetch conntrack after insertion In case the conntrack is clashing, insertion can free skb->_nfct and set skb->_nfct to the already-confirmed entry. This wasn't found before because the conntrack entry and the extension space used to free'd after an rcu grace period, plus the race needs events enabled to trigger. Reported-by: Fixes: 71d8c47fc653 ("netfilter: conntrack: introduce clash resolution on insertion race") Fixes: 2ad9d7747c10 ("netfilter: conntrack: free extension area immediately") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- diff --git a/include/net/netfilter/nf_conntrack_core.h b/include/net/netfilter/nf_conntrack_core.h index 6406cfee34c2d..37866c8386e23 100644 --- a/include/net/netfilter/nf_conntrack_core.h +++ b/include/net/netfilter/nf_conntrack_core.h @@ -58,8 +58,13 @@ static inline int nf_conntrack_confirm(struct sk_buff *skb) int ret = NF_ACCEPT; if (ct) { - if (!nf_ct_is_confirmed(ct)) + if (!nf_ct_is_confirmed(ct)) { ret = __nf_conntrack_confirm(skb); + + if (ret == NF_ACCEPT) + ct = (struct nf_conn *)skb_nfct(skb); + } + if (ret == NF_ACCEPT && nf_ct_ecache_exist(ct)) nf_ct_deliver_cached_events(ct); }