* [PATCH nf] netfilter: socket: icmp6: fix use-after-scope
@ 2021-09-03 13:23 Benjamin Hesmans
2021-09-03 14:00 ` Florian Westphal
2021-09-03 16:24 ` Pablo Neira Ayuso
0 siblings, 2 replies; 3+ messages in thread
From: Benjamin Hesmans @ 2021-09-03 13:23 UTC (permalink / raw)
To: netfilter-devel; +Cc: Matthieu Baerts, Benjamin Hesmans
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(-)
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;
--
2.17.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH nf] netfilter: socket: icmp6: fix use-after-scope
2021-09-03 13:23 [PATCH nf] netfilter: socket: icmp6: fix use-after-scope Benjamin Hesmans
@ 2021-09-03 14:00 ` Florian Westphal
2021-09-03 16:24 ` Pablo Neira Ayuso
1 sibling, 0 replies; 3+ messages in thread
From: Florian Westphal @ 2021-09-03 14:00 UTC (permalink / raw)
To: Benjamin Hesmans; +Cc: netfilter-devel, Matthieu Baerts
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>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH nf] netfilter: socket: icmp6: fix use-after-scope
2021-09-03 13:23 [PATCH nf] netfilter: socket: icmp6: fix use-after-scope Benjamin Hesmans
2021-09-03 14:00 ` Florian Westphal
@ 2021-09-03 16:24 ` Pablo Neira Ayuso
1 sibling, 0 replies; 3+ messages in thread
From: Pablo Neira Ayuso @ 2021-09-03 16:24 UTC (permalink / raw)
To: Benjamin Hesmans; +Cc: netfilter-devel, Matthieu Baerts
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.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-09-03 16:25 UTC | newest]
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2021-09-03 13:23 [PATCH nf] netfilter: socket: icmp6: fix use-after-scope Benjamin Hesmans
2021-09-03 14:00 ` Florian Westphal
2021-09-03 16:24 ` Pablo Neira Ayuso
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