From: Benjamin Hesmans benjamin.hesmans@tessares.net
stable inclusion from linux-4.19.207 commit d6efada330af09253b0f81a0d836cee02192bd4f
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[ Upstream commit 730affed24bffcd1eebd5903171960f5ff9f1f22 ]
Bug reported by KASAN:
BUG: KASAN: use-after-scope in inet6_ehashfn (net/ipv6/inet6_hashtables.c:40) Call Trace: (...) inet6_ehashfn (net/ipv6/inet6_hashtables.c:40) (...) nf_sk_lookup_slow_v6 (net/ipv6/netfilter/nf_socket_ipv6.c:91 net/ipv6/netfilter/nf_socket_ipv6.c:146)
It seems that this bug has already been fixed by Eric Dumazet in the past in: commit 78296c97ca1f ("netfilter: xt_socket: fix a stack corruption bug")
But a variant of the same issue has been introduced in commit d64d80a2cde9 ("netfilter: x_tables: don't extract flow keys on early demuxed sks in socket match")
`daddr` and `saddr` potentially hold a reference to ipv6_var that is no longer in scope when the call to `nf_socket_get_sock_v6` is made.
Fixes: d64d80a2cde9 ("netfilter: x_tables: don't extract flow keys on early demuxed sks in socket match") Acked-by: Matthieu Baerts matthieu.baerts@tessares.net Signed-off-by: Benjamin Hesmans benjamin.hesmans@tessares.net Reviewed-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- net/ipv6/netfilter/nf_socket_ipv6.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/net/ipv6/netfilter/nf_socket_ipv6.c b/net/ipv6/netfilter/nf_socket_ipv6.c index f14de4b6d639d..58e839e2ce1d3 100644 --- a/net/ipv6/netfilter/nf_socket_ipv6.c +++ b/net/ipv6/netfilter/nf_socket_ipv6.c @@ -104,7 +104,7 @@ struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb, { __be16 uninitialized_var(dport), uninitialized_var(sport); const struct in6_addr *daddr = NULL, *saddr = NULL; - struct ipv6hdr *iph = ipv6_hdr(skb); + struct ipv6hdr *iph = ipv6_hdr(skb), ipv6_var; struct sk_buff *data_skb = NULL; int doff = 0; int thoff = 0, tproto; @@ -134,8 +134,6 @@ struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb, thoff + sizeof(*hp);
} else if (tproto == IPPROTO_ICMPV6) { - struct ipv6hdr ipv6_var; - if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr, &sport, &dport, &ipv6_var)) return NULL;