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@xxxxxxxxxxxxxxxxx>
Acked-by: Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxxxxxx>
Best regards,
Jozsef
> Reported-by: syzbot+34bd2369d38707f3f4a7@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: a7b4f989a6294 ("netfilter: ipset: IP set core support")
> Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
> ---
> 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@xxxxxxxxxxxxxxxxx, kadlecsik.jozsef@xxxxxxxxxxxxx
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Address : Wigner Research Centre for Physics
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