From: "Kadlecsik József" <kadlec@blackhole.kfki.hu>
To: Florian Westphal <fw@strlen.de>
Cc: netfilter-devel@vger.kernel.org, netdev@vger.kernel.org,
syzkaller-bugs@googlegroups.com,
syzbot+34bd2369d38707f3f4a7@syzkaller.appspotmail.com
Subject: Re: [PATCH nf] netfilter: ipset: avoid null deref when IPSET_ATTR_LINENO is present
Date: Wed, 8 Jan 2020 11:05:19 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.2001081102010.27242@blackhole.kfki.hu> (raw)
In-Reply-To: <20200108095938.3704-1-fw@strlen.de>
On Wed, 8 Jan 2020, Florian Westphal wrote:
> The set uadt functions assume lineno is never NULL, but it is in
> case of ip_set_utest().
>
> syzkaller managed to generate a netlink message that calls this with
> LINENO attr present:
>
> general protection fault: 0000 [#1] PREEMPT SMP KASAN
> RIP: 0010:hash_mac4_uadt+0x1bc/0x470 net/netfilter/ipset/ip_set_hash_mac.c:104
> Call Trace:
> ip_set_utest+0x55b/0x890 net/netfilter/ipset/ip_set_core.c:1867
> nfnetlink_rcv_msg+0xcf2/0xfb0 net/netfilter/nfnetlink.c:229
> netlink_rcv_skb+0x177/0x450 net/netlink/af_netlink.c:2477
> nfnetlink_rcv+0x1ba/0x460 net/netfilter/nfnetlink.c:563
>
> pass a dummy lineno storage, its easier than patching all set
> implementations.
I have just written the same patch... you were faster.
> This seems to be a day-0 bug.
Yes, alas. One could extend the check of attributes in ip_set_utest() to
bail out with protocol error if attr[IPSET_ATTR_LINENO] is present.
> Cc: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Best regards,
Jozsef
> Reported-by: syzbot+34bd2369d38707f3f4a7@syzkaller.appspotmail.com
> Fixes: a7b4f989a6294 ("netfilter: ipset: IP set core support")
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
> net/netfilter/ipset/ip_set_core.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
> index 169e0a04f814..cf895bc80871 100644
> --- a/net/netfilter/ipset/ip_set_core.c
> +++ b/net/netfilter/ipset/ip_set_core.c
> @@ -1848,6 +1848,7 @@ static int ip_set_utest(struct net *net, struct sock *ctnl, struct sk_buff *skb,
> struct ip_set *set;
> struct nlattr *tb[IPSET_ATTR_ADT_MAX + 1] = {};
> int ret = 0;
> + u32 lineno;
>
> if (unlikely(protocol_min_failed(attr) ||
> !attr[IPSET_ATTR_SETNAME] ||
> @@ -1864,7 +1865,7 @@ static int ip_set_utest(struct net *net, struct sock *ctnl, struct sk_buff *skb,
> return -IPSET_ERR_PROTOCOL;
>
> rcu_read_lock_bh();
> - ret = set->variant->uadt(set, tb, IPSET_TEST, NULL, 0, 0);
> + ret = set->variant->uadt(set, tb, IPSET_TEST, &lineno, 0, 0);
> rcu_read_unlock_bh();
> /* Userspace can't trigger element to be re-added */
> if (ret == -EAGAIN)
> --
> 2.24.1
>
>
-
E-mail : kadlec@blackhole.kfki.hu, kadlecsik.jozsef@wigner.mta.hu
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics
H-1525 Budapest 114, POB. 49, Hungary
next prev parent reply other threads:[~2020-01-08 10:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-07 16:03 general protection fault in hash_ipportnet4_uadt syzbot
2020-01-07 17:28 ` syzbot
2020-01-08 9:59 ` [PATCH nf] netfilter: ipset: avoid null deref when IPSET_ATTR_LINENO is present Florian Westphal
2020-01-08 10:05 ` Kadlecsik József [this message]
2020-01-08 10:37 ` [PATCH] " Jan Engelhardt
2020-01-08 12:43 ` Kadlecsik József
2020-01-08 22:32 ` [PATCH nf] " Pablo Neira Ayuso
2020-01-08 16:53 ` general protection fault in hash_ipportnet4_uadt syzbot
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