| Message ID | 20210903132335.25355-1-benjamin.hesmans@tessares.net |
|---|---|
| State | Accepted |
| Delegated to: | Pablo Neira |
| Headers | show |
| Series | [nf] netfilter: socket: icmp6: fix use-after-scope | expand |
Benjamin Hesmans <benjamin.hesmans@tessares.net> wrote: > 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) Similar construct in the branch above is fine because sport and dport are copied (rather than passing pointer to address). Reviewed-by: Florian Westphal <fw@strlen.de>
On Fri, Sep 03, 2021 at 03:23:35PM +0200, Benjamin Hesmans wrote: > 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. Applied, thanks.
diff --git a/net/ipv6/netfilter/nf_socket_ipv6.c b/net/ipv6/netfilter/nf_socket_ipv6.c index 6fd54744cbc3..aa5bb8789ba0 100644 --- a/net/ipv6/netfilter/nf_socket_ipv6.c +++ b/net/ipv6/netfilter/nf_socket_ipv6.c @@ -99,7 +99,7 @@ struct sock *nf_sk_lookup_slow_v6(struct net *net, const struct sk_buff *skb, { __be16 dport, 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;
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> --- net/ipv6/netfilter/nf_socket_ipv6.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)