From 2c3c5ea34d152b95e2e55f6de712db88f5f602be Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Sun, 23 Jan 2022 15:24:00 +0100 Subject: [PATCH] netfilter: nft_ct: fix use after free when attaching zone template [ Upstream commit 34243b9ec856309339172b1507379074156947e8 ] The conversion erroneously removed the refcount increment. In case we can use the percpu template, we need to increment the refcount, else it will be released when the skb gets freed. In case the slowpath is taken, the new template already has a refcount of 1. Fixes: 719774377622 ("netfilter: conntrack: convert to refcount_t api") Reported-by: kernel test robot Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Stable-dep-of: 5cfe5612ca95 ("netfilter: nft_ct: Use __refcount_inc() for per-CPU nft_ct_pcpu_template.") Signed-off-by: Sasha Levin --- net/netfilter/nft_ct.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c index 78631804e5c53..4b75c7113de4d 100644 --- a/net/netfilter/nft_ct.c +++ b/net/netfilter/nft_ct.c @@ -260,9 +260,12 @@ static void nft_ct_set_zone_eval(const struct nft_expr *expr, ct = this_cpu_read(nft_ct_pcpu_template); if (likely(refcount_read(&ct->ct_general.use) == 1)) { + refcount_inc(&ct->ct_general.use); nf_ct_zone_add(ct, &zone); } else { - /* previous skb got queued to userspace */ + /* previous skb got queued to userspace, allocate temporary + * one until percpu template can be reused. + */ ct = nf_ct_tmpl_alloc(nft_net(pkt), &zone, GFP_ATOMIC); if (!ct) { regs->verdict.code = NF_DROP; -- 2.47.3