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Commit d448b240 authored by Benjamin Hesmans's avatar Benjamin Hesmans Committed by Greg Kroah-Hartman
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netfilter: socket: icmp6: fix use-after-scope 



[ 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 78296c97 ("netfilter: xt_socket: fix a stack corruption bug")

But a variant of the same issue has been introduced in
commit d64d80a2 ("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: d64d80a2 ("netfilter: x_tables: don't extract flow keys on early demuxed sks in socket match")
Acked-by: default avatarMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: default avatarBenjamin Hesmans <benjamin.hesmans@tessares.net>
Reviewed-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent b7920416

net/ipv6/netfilter/nf_socket_ipv6.c

+1 −3
Original line number Diff line number Diff line
@@ -99,7 +99,7 @@ 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;
@@ -129,8 +129,6 @@ 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;