From f51495c1ba41eb3b094db7d3021c7849ea3d9450 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Wed, 8 Jan 2020 10:59:38 +0100
Git-commit: 22dad713b8a5ff488e07b821195270672f486eb2
Patch-mainline: v5.5-rc6
References: git-fixes
Subject: [PATCH] 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 <kadlec@blackhole.kfki.hu>
Reported-by: syzbot+34bd2369d38707f3f4a7@syzkaller.appspotmail.com
Fixes: a7b4f989a6294 ("netfilter: ipset: IP set core support")
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
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 d73d1828216a..d8143a8c034d 100644
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -1658,6 +1658,7 @@ 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] ||
@@ -1674,7 +1675,7 @@ 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)
--
2.16.4