From c5a02e144277effbe22c321e1675cbb80a361745 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 9 Jan 2020 00:17:13 +0100 Subject: netfilter: ipset: avoid null deref when IPSET_ATTR_LINENO is present 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. This seems to be a day-0 bug. Cc: Jozsef Kadlecsik Reported-by: syzbot+34bd2369d38707f3f4a7@syzkaller.appspotmail.com Fixes: a7b4f989a6294 ("netfilter: ipset: IP set core support") Signed-off-by: Florian Westphal Acked-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso Signed-off-by: Jozsef Kadlecsik --- kernel/net/netfilter/ipset/ip_set_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'kernel/net') diff --git a/kernel/net/netfilter/ipset/ip_set_core.c b/kernel/net/netfilter/ipset/ip_set_core.c index 4d8e8b1..e367f3b 100644 --- a/kernel/net/netfilter/ipset/ip_set_core.c +++ b/kernel/net/netfilter/ipset/ip_set_core.c @@ -1871,6 +1871,7 @@ IPSET_CBFN(ip_set_utest, struct net *net, struct sock *ctnl, 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] || @@ -1887,7 +1888,7 @@ IPSET_CBFN(ip_set_utest, struct net *net, struct sock *ctnl, 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) -- cgit v1.2.3